CA2119958A1 - Micro-controller based high voltage power supply - Google Patents
Micro-controller based high voltage power supplyInfo
- Publication number
- CA2119958A1 CA2119958A1 CA 2119958 CA2119958A CA2119958A1 CA 2119958 A1 CA2119958 A1 CA 2119958A1 CA 2119958 CA2119958 CA 2119958 CA 2119958 A CA2119958 A CA 2119958A CA 2119958 A1 CA2119958 A1 CA 2119958A1
- Authority
- CA
- Canada
- Prior art keywords
- high voltage
- power supply
- voltage power
- output
- controller
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Abstract
MICRO-CONTROLLER BASED
HIGH VOLTAGE POWER SUPPLY
ABSTRACT OF THE DISCLOSURE
A high voltage power supply for use in electrostatically-aided coating material application equipment for dispensing electrostatically charged particles of coating material includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. A non-volatile memory is provided for storing current parameter settings, turn on table values, and a constants table for use by the controller. A
personal computer is connectible to the controller over a communication link to permit changing dynamically of the values stored in the non-volatile memory while in operation so as to facilitate engineering development and service.
HIGH VOLTAGE POWER SUPPLY
ABSTRACT OF THE DISCLOSURE
A high voltage power supply for use in electrostatically-aided coating material application equipment for dispensing electrostatically charged particles of coating material includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. A non-volatile memory is provided for storing current parameter settings, turn on table values, and a constants table for use by the controller. A
personal computer is connectible to the controller over a communication link to permit changing dynamically of the values stored in the non-volatile memory while in operation so as to facilitate engineering development and service.
Description
`
MICRO-CONTROLLER BASED
HIGH VOLTAGE POWER SUPPI.Y
_ . .
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates yenerally to power supply systems and more particularly, it relates to a micro-controller based high voltage power supply for use in electrostatically-aided coating material applicat:io~
equipment for dispensing electrostatically charged particles of coating material which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics.
MICRO-CONTROLLER BASED
HIGH VOLTAGE POWER SUPPI.Y
_ . .
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates yenerally to power supply systems and more particularly, it relates to a micro-controller based high voltage power supply for use in electrostatically-aided coating material applicat:io~
equipment for dispensing electrostatically charged particles of coating material which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics.
2. Description of the Prior Art:
As is generally known in industrial electrostatic coating systems, high voltage direct current power supplies are used to produce high magnitude potentials of up to 150 kilovolts (KV) DC across a pair of ~e~minals.
Typically, one of the terminals is held at a high negative potential which is supplied to a rotating atomizer (bell) for charging particles o~ the coating material as they are dispensed. An electrostatic field is created between the rotating atomizer and a target -- object (articles to be coated). The other one of the terminals is maintained at a low potential, typically at or near ground, as is the target object A fluid system deliver~ the coating material to the rotating atomizer and its rotation feeds the fluid u~iformly to its outer edge. The coating material is atomized and charged by the electrostatic field to form a mist of electrically charged particles. This charged coating material is attracted to and deposited on the target object.
A safety hazard exists by the possibility o~ a high voltage spark discharge across the space between the rotating atomizer and the target object due to their relative movement. This may be caused by the potential across the space between the rotating atomizer and the target object exceeding the dielectric of the space, such as when the target moves too close to the atomizer or when the magnitude of the potential on the atomizer is allowed to reach too high a level. Thus, there has arisen a need to provide a power supply system which can detect the existence of unsa~e conditions and prevent them from occurring.
As is generally known in industrial electrostatic coating systems, high voltage direct current power supplies are used to produce high magnitude potentials of up to 150 kilovolts (KV) DC across a pair of ~e~minals.
Typically, one of the terminals is held at a high negative potential which is supplied to a rotating atomizer (bell) for charging particles o~ the coating material as they are dispensed. An electrostatic field is created between the rotating atomizer and a target -- object (articles to be coated). The other one of the terminals is maintained at a low potential, typically at or near ground, as is the target object A fluid system deliver~ the coating material to the rotating atomizer and its rotation feeds the fluid u~iformly to its outer edge. The coating material is atomized and charged by the electrostatic field to form a mist of electrically charged particles. This charged coating material is attracted to and deposited on the target object.
A safety hazard exists by the possibility o~ a high voltage spark discharge across the space between the rotating atomizer and the target object due to their relative movement. This may be caused by the potential across the space between the rotating atomizer and the target object exceeding the dielectric of the space, such as when the target moves too close to the atomizer or when the magnitude of the potential on the atomizer is allowed to reach too high a level. Thus, there has arisen a need to provide a power supply system which can detect the existence of unsa~e conditions and prevent them from occurring.
While there are known in the prlor art of systems which can predict the existence o~ certain unsafe _. conditions, these systems were ~mplemented u~ing all analog and discrete digital circui~ry to perform complex functions, resulting in large component counts and oc-cupying a large amount of space on printed circuit boards. F~rther, the manufacturing and a~;sembly of these prior art 6ystems are quite high in cost. In addition, these prior art systems lack versa~ility 50 as to adapt to change in the system design or application as well as lacking of diagnostic information concerning problems or ~ailures.
A prior art search directed to the subject matter o~
this application in the U.S. Patent and Trademark Office revealed the following U.S. Letters Patent: ::
A prior art search directed to the subject matter o~
this application in the U.S. Patent and Trademark Office revealed the following U.S. Letters Patent: ::
4,409,63S 4,698,517 4,472,781 4,797,B33 ~ .
4,538,231 4,891,743 -4,587,605 5,019,996 4,630,220 5,107,438 . . .
~ ~ '3~
In U.S. Patent No. 4,409,635 to Kraus issued on October 11, 1983, there is disclosed an electrical power -- system which includes a microprocessor-based control unit for maintaining power output and performing control functions. The control unit is comprised of a micro-processor, digital comparator, read-on].y memory, output means for producing control signals, and a feedback circuit which implements the locking ~eature. The control unit conducts a series of self-test routines which evaluate the opera~ing condition of the system components. The control unit utilizes a sequential key word kechnique to provide a means of failure detection.
In U.S. Patent No. 4,472,781 to ~iller issued on September 18, 19~4, there is disclosed a power supply system for electronic postage meters which includes a switching type regulated power supply for generating switched regulated D.C. output voltages. The postage meter has a control module which includes a micro~
processor and control circuits.
In U.S. Patent No. 4,891,743 to May et al. issued on January 2, 1~2, there is disclosed a control system for an industrial inverting type power supply which provides _5- CASE 751 both operational control and a diagnostic capability for the power supply. The control system includes a -- controller 1 which is interfaced to an ~nverter type industrial power supply 2 and to an external system 3 through an input isolation circuit 4 and an output isolation circuit 5. The controller also inter~aces to a locàl display 20 and a remote display 21 via respective RS-485 serial communica~ion lin~s 22 and 23. The dis-plays 20 and 21 are used to display certain operational and diagnostic information. Each of the displays contains switches and controls for operator input and a display screen for displaying operational and diagnostic information to the operator. The controller 1 also communicates with a local terminal 25 and a remote terminal 26 each being a personal computer system. The controller is comprised of a microprocessor 101 having a system bus 101 connected to a ROM 105, a RAM 106, and EEPROM 107.
Further, there are known in the prior art of electrical power supplies for generating high magnitude electrostatic potential for use in industrial electro-static coating systems as illustrated in U.S. Patent Nos.
4,187,527; 4,485,427; and 4,745,520 all owned by the assignee of the present invention. In '527 patent, there 3 ~ ~
is described a system 10 for electrostatic deposition o~
a coating on an article from a charging device which includes a shorting device 36 for reducing the potential across the output terminals 32 and 34 of a high voltage circuit 30 in response to control signals ~rom ~ control circuit 40. The control circuit includes a slope-detecting circuit 44 responsive to a sensed current to detect ~oo-rapid changes therein indicating of possible high voltage arcing. The control circuit also includes an automatic ranging circuit which compares a sampled signal related to the actual current through a sensi.ng resistor with a signal related to a predatermined multiple of the instantaneous current through the sensing resistor.
lS In the '427 patent, there is shown a power supply for a coating material dispenser for dispensing electro~
statically charged particles of coating material which includes an electrostatic potential generator having a "fold-back" voltage-current characteristic including a reduced voltage-reduced current curve region wherein the energy available at the dispenser is less than that necessary for spark ignition. In the '520 patent, there is illustrated a high magnitude electrostatic potential supply, an electrostatic potential utilization device, 3 ~
and a coupling device connecting the electrostatic potential supply to the utilization device. ~he coupling -- device consists essentially o~ a conductor having sub- -stantially no distributed capacitance and substantially no distributed resistance.
~- ~ r However, none of the prior art discussed above teach a high voltage power supply for use in electrostatically-aided coating material system equipment for dispensing electrostatically charged particles of coating material like that of the pxesent invention which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. Further, a personal computer is connectible to the controller for a communication link so as to facilitate engineering development and service.
The.present invention represents significant improvements over the '527, '427, and '520 patents, which are hereby incorpo~ated by reference.
SUMMARY OF THE INVEN?ION
Accordingly, it is a general object of the present invention t~ provide an improved high voltage power , : : ; . . . , ~
i 8 supply for use in electrostatically-aided coating material application equipment for dispensi~g electro-_. statically charged particles of coating material whichincludes a control ~odule having a controller operated under a stored program to perform all control, safety and oper~ting diagnostics.
~ ~ r ~ -~
It is an object of the present invention to provide an improved high voltage power supply for dispen~ing electrostatically charged particles of coating material which is implemented with a reduced number of discrete components and occupying less printed circuit board space than has been traditionally available.
It is another object of the present invention to provide an improved high voltage power supply for dispensing electrostatically charged particles of coating material which includes a personal computer connectible to a controller over a communication link so as to alter all control and safety diagnostic parameters as well as retrieving stored diagnostic in~ormation.
- . , .. , ~
It is still another object oP the present i-nvention to provide an improved high voltage power supply for dis-pensing electrostatically charged particles o~ coating ~aterial which includes a non-volatile me~ory ~or ~toring current parameter 6etting5, normail ~urn-on table values, fault turn-on table values, and a constants table.
, . . .
It is yet still anothier.object o~ the present invention to provide an improved high voltage power supply for dispensing electrostatically charged particles ~0 of coating material which is formed of a con~rol module having a controller, a high voltage module for generating a high voltage output, and a programmable bandpa~s filter coupled to the high voltage module ~or supplying current and voltage feedbacX signals to the controller.
It is still yet another object of the present invention to provide improved high voltage power supply for dispensing electrostatically charged particles of coating material which includes a controller ~or generating first and second complementary drive signals ~-having a programmable dead space time therebetween. ~-.. . .............. . .
~' ' ' ' ~ . ' 2.~.~.9~v~
-lO- CASE 751 In accordance with a preferred embodiment of the present invention, there is provided a high voltage power -- supply for use in electrostatically-aided coating material application equipment for di~spensing electro-statically charged particles of coating material which includes an electrostatic potential utilization device, ~ ~ r a high voltage module, a high voltage cable ~or coupling the hig~ voltage module to the utiliz~tion device, a low voltage D.C. power source, and a control module. The high voltage module includes a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output. The control module includes a switching type regulator which is responsive to the D.C.
lS power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver cirGuits for switching the regulated operating voltage across the primary winding.
-:
The control module also includes a controller for generating first and second drive signals for the first and second switching driver circuits. A non-volatile memory i5 provided ~or storing current parameter settinqs, normal turn-on table values, fault turn-on table values, and a constants table. The controller is Y ~
:, .
adapted to perform safety an~ operatiing diagnostic through a stored program based upon the settings and _ .values obtained from the non-volatile memory.
BRIEF DESCRIPTION OF THE D~WINGS
.
These and other objects and adivantages of the present invention will become more fully apparent ~ro~
the following detailed description when read in con-junction with the accompanying drawings with like reference numerals indicating corresponding parts throughout, wherein:
Figure 1 is a simplified block diagram of a micro-controlled based high voltage power supply, constructed in accordance with the principles of the present invention;
Figure 2 i5 a more detailed block diagram of the high voltage power supply of Figure 1;
Figure 3 shows the waveforms ~a3 and (h) of the complementary drive signals appearing at the outputs of the first and second switching dri~er circuits of Figure 2;
?~ i 8 Figure 4 is a pictorial representation of a front . panel used in the high voltage power supply of Fi~ures 1 ~- and 2;
Figures 5(a)-5(g) are detailed sc:hematic circuit diagrams showing suitable circuitry for use in certain ones of the blocks of Figure 2;
Figure 6 illustrates an output potential-current characteristic of the present high voltage power supply;
Figure 7 is a graphical representation o~` a first menu, illustrating Tables 1 through 3;
-~ . - ' .
::: , :
Figure 8 is a graphical representation of a second `~
menu, illustrating Table 4; and Figure 9 is a graphical representation oP a third menu, illustrating Table 5;
.
DESCRIPTION OF THE PREFERRED_EMBODIMENT :~
Referring now in detail to the drawings, there is shown in Figure 1 a block diagram o~ a micro-controller based high voltage power supply 10 for use in J" 'LiC3 ~
electrostatically-aided coating material application equipment for dispensing electrostatically charged . particles of coating material, constructed in accordance with the principles o~ the present invention. The micro-controller based high voltage power supply is used tosupply up to 100,000 D.C. at 300 uA so as to assist in the atomization and transfer efficiencies of the electro-static coating application equipment. The high voltage power supply 10 is comprised o~ a control module 12, a high voltage module 14, and an electrostatic potential utilization device 16 such as a coating atomizer.
A low voltage power supply 18 is provided to produce a relatively low voltage of +24 volts D.C. which is connected to the control module 12 via line 20. The high voltage module 14 includes a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output. The high voltage module has an input terminal 22 which is connected to the control module 12 by a low voltage cable 26. The high voltage module also includes an output terminal 24 for supplying the high voltage output to the coating atomi~er 16 via a high voltage-cable 28. The coating atomizer 16 serves to produce atomized particles of a coating material, such as liquid paint or powder, which will be attracted toward and deposited electrostatically upon an article or target -- 30 to be coated. The arti~le 30 is typically moved past the coating atomizer 16 on a conveyor (not shown).
~ ~ r ~he control module 12 is controlled externally by input~oùtput (I/O) devices connectible via line 32 so as to perform control of the entire coating process. A
personal computer may optionally be provided for communication with the control module 12 via a serial da~a link 36. The personal computer is especially use~ul by appropriate personnel in an engineering development environment so as to easily alter many different control, safety and operating diagnostic parameters in order to adapt the power supply for a particular application.
In Figure 2, there is shown a more detailed block diagram of the power supply 10 of Figure 1. The control ~odule 12 includes a micro-controller 38 which is preferably an Intel type AN87C196KR. The micro-controller 38 generates two complementary drive signals on lines 40 and 42, which may be programmable with a "dead space" ~small period of time when nei~her signal is active) during the cross-over portions thereof. These ," . ., ., ~ . . , . ~ ~, : , . , 2 ~
drive signals are illus~rated in Figures 3(a) and 3(b), respectively. The control module 12 includes a first switching driver circuit 44 connected to the line 40 and ; ~
a second switching driver circuit 46 connected to the line 42. The hig~ voltage module 14 includes the high voltage transformer 48 having a primary winding P and a secondary winding S. The primary winding P has a first end 50, a second end 52, and a center tap 54. The first end 50 is connected to the output of the first switching driver circuit 44 via line 56, and the second end 52 is connected to the output of the second switching driver circuit 46 via line 58.
The control module 12 ~urther includes a program-mable frequency/pulse wid~h generator 60 and a switching inverter type regulator 62. The pulse width generator 60 has its input connected to the micro-controller 38 via line 64 and its output connected via line 65 to the input of the switching regulator 62. The output of the switch-ing regulator 62 provides a regulated operating voltage which is fed to the center tap 54 of the primary winding P via line 66. The center tap voltage is regulated by a regulator feedback signal on line 68 from the switching regulator, which is generated by a resistive voltage divider circuit located in the switching regulator. This - ) regulator feedback signal is sent to the micro-controller 38.
A feedback voltage on line 70 is generated by the high voltage module 14, which represents an output current signal. This output current feedback signal is generat-ed via a resistance connected in series with the xeturn path in the high voltage multiplier circuit of the high voltage module to ground. This current feedback voltage is fed to a programmable bandpass filter 72 and then to the micro-controller 38 via a bu~fer 74. This current feedback voltage representing output current is used by the micro-controller 38 to display the value and to perform safety dia~nostics as will be descri~ed here-inafter. Another feedback voltage on line 76 is also generated by the high voltage module 14 and represents an output XV signal which is used to display the value and to perform the closed-loop control algorithms necessary to regulate the center-tap voltage for a stable high voltage output at the output terminal 24. This fPedback volta~e is fed to the micro-controller 38 via a buffer 77.
Digital I/O circuits 78 and analog I/O circuits 80 are coupled between the micro-controller and a user block -- 82 for supplying status signals to the user and for receiving external control signals to the micro-controller. A display decoder/driver 84 is used to inter~ace KV and I displays 86a and 86b with the micro-~, ~ r controller. Lamp driver~ 88 are used to interface the micro-controller with front panel lamps 90a-9Oe. A
parallel-to-serial converter circuit 91 is used to inter~ace the micro-controller with the front panel swit~hes 92a-92h. A non-volatile RAM 94 is provided for storing al} of the operating and diagnostic information which is controlled by the micro-controller via line 96.
A digital expansion port 98 is used to provide a communi-cation link via lines lOo and 102 when special controlinterfaces are required. A serial communication por~ 104 is used to interface the micro-controller via lines 106 and 108 with the personal computer 3~.
A pictorial representation of a front panel 110 used in the power supply of Figures 1 and 2 is illustrated in Figure 4. Referring now to Figures 2 and 4, the output KV display 86a is a 3-digit display for indicating the actual voltage for the desired set voltage which is between 20 to 100 KV. This setting can be changed by de-'`~` J~ 'J7 ~_7 ~3 -18- ~ASE 751 pressing the ADJUST-UP pushbutton s2a or the ADJUST-DOWN
_. pushbutton 92b. When the pushbutton s2a is depre~sed, the output XV display 86a will have its decimal point lit and~will display the stored value which can be ~hen incremented continuously. When the puGhbutton 92b is depressed, the output XV di~play 86a will indicate the 6tored val~e which can be then decrement~d continuously.
Once the pushbutton 92a or 92b is relea~,ed, the present set value of the desired voltage will be stored in the non-volatile RAM 94. A momentary ~V ON pushbutton 9~c i.s depressed so as to supply the high voltage output ~rom th~ high voltage module 14 to the coating atomizer 16.
A ~omentary HV OFF pushbutton 92d is depressed 50 as to disconnect the high voltage from the high voltage module to the coating atomizer.
The output CURRENT display 86b is a 3-digit display ~or indicating the actual current or the desired set current which is between 50 to 1000 uA. When the CURRENT
LIMIT pushbutton 92e (located under a removable panel door 112) is depressed, this allows the operator to set the maximum current whi~h the power supply 10 will deliver. Similarly, when the pushbutton g2a i8 depressed, the output CURRENT display 86h wîll have its decimal point lit and will display the stored value which . ::: ~ : : : :
: ~ .~ , , -.
: ~ ) can be then incremented continuously. When the pushbutton 92b is depressed, the output CURRENT display -- 86b will indicate the stored value w]hich can be then decremented continuously. Once the pushbutton 92a or 92b is released, the present value of the~ desired current will al~o be stored in the non-volatile RAM 94.
~I ~ t As can be seen from Figure 6, there is shown the output high potential-output current characteristic which the present power supply seeks to provide referred to as a so-called "fold-back" characteristic. That is, this characteristic is where the output vol~age/output current varies generally linearly along an increasing current-decr~asing potential line 610. This is achieved by setting a SLOPE reduction point 612. It will be noted that the output voltage decreases along the line 610 when the current increases beyond this SLOPE reduction point 612. The value of the CURRENT LINIT setting will always be the final cut-off point 614 for the curren~. At this point 614 (intersection of the horizontal 20 KV line and the vertical current limit line~, the overload condition will be reached and the high voltage will be disabled or switched to zero and the F~ULT lamp 90c will be turned on~
~, ~ ` ~'3~ 9 ~ ~
Again, this SLOPE reduction point 612 can be set by the operator by depressing the SLOPE pushbutton 92f and _- either the pushbutton 92a or 92b. When the pushbutton 92a is depressed, the output KV display 96a will be blànked and the stored value of the SLOPE reduction setting will be displayed which can be then incremented ~1 ~ r continuously. When the pushbutton s2b is depressed, the stored ~alue of the SLOPE setting will be indicated on the display 86a and the value thereof can be then decre-mented continuously. When the pushbutton 92a or 92b isreleased, the present value of the SLOPE setting will be likewise stored in the non-volatile RAM 94.
The CORONA SENSE setting has a stored value between 1 and 100, which corresponds to an output voltage between 0 to 5 volts of the bandpass filter 72. The stored value is a measure of the chaos in the operating environment of the high voltage power supply 10. This chaos represents the presence of corona on the high voltage cable 28 and that corona is a precursor to a sparX. ~hen the corona sense is within 80% of the setting, th~ CORONA SENSE lamp 90e will be flashing at a rate o~ approximately one hertz. When the corona sense is within 90% of the setting, the -lamp 90e will be flashing at approximately two hertz. When the corona se~se reaches the setting, ,. . . . .
7.~ 9~3~ _) -21- ~ASE 751 the high voltage will be disabled and the FAULT la~p 9Oc -- and the CORONA SENSE amp 90e will both be lit.
The corona sense value is ~et by the operator by ~ ~ s depres~ing ~he CORONA pushbutton 92g and either the pushbutton 92a or 92b. When the pushbutton 92a is depressed, ~he output KV display 86a will again be blanked and the stored value of the corona ~ense setting ~ ~
will be displayed which can be then incrementecl con- ~ -. ~
tinuously. When the pushbutton 92b is depressed, the stored value of the corona sense setting will be indicated on the display 86a and the value thereof can be then decremented continuously. When the pushbutton 92a or 92b is released, the present value of CORONA SENSE
setting will also be stored in the non-volatile RAM 94.
While th~ various blocks 38, 44, 46, 60, 62, 84-92, 94 and 98 ~ay take on various forms, suitable circuitry therefor is illustrated in Figur~s 5~a) through 5(g).
EYen though these schematics are believed to be self~
explanatory to those skilled in the art in view of the foregoing description, a brief de~cription of the opera-tion of several of these blocks is believed to be in order.
~f~,~3 ~ 8 ; , ,, Referring now to Figures 2 and 5(a)-5(g), there is _- shown an integrated circuit U4 which corresponds to the micro-controller 38 (Figure 2) and is preferably an Intel type AN87C196KR. The pin numbers illustrated in the ~ :
drawings are those applicable when this particular integrated circuit i5 employed for this purpose. This convention will be used when referring to the various integrated circuits described throughout this description of the preferred embodiment. However, it should be clearly understood that other integrated circuits could be employed ~or these purposes for which the various integrated circuits described herein are used. :
The micro-controller U4 has three high speed serial ports P6.7/SD1 (signal DO), P6.~/SCl (signal SK), and P6.5/SD0 (signal DI) which are used to load information into two digital pulse width modulator integrated circuits U13 and U14. The integrated circuits U13 and U17 are preferably a Harris type CDP68HC68WlE, which are used to modulate the 8 MHz clock output from pin P2.7/CLKOUT of the ~icro-controller U4 in order to supply a variable frequency and duty output sisnal on its respective pin 7. The output signal CLX-IN-I on pin 7 of Ul3 has a frequency which is variable between 5 KHz and : ~, ... . ~ .,: ,. ~ : , : ... , :
2 ~ `9 3 ~
. ~
100 gHz corresponding to a center frequency of the corona programmable bandpass filter U18 (72 of Figure 2) of -- '0.1 KHz to 2 KHz. The integrated circu.it U18 is prefer-ably a National typa LMFlOOCN which rec:eives the output signal CLK-IN-I on its pin CLKa. The integrated circuit U13 is selected by the chip select pin 1'2.3/INTB (signal CS3) of the micro-controller U4.
Similarly, the output signal CT-DRIVE on pin 7 of U17 has a frequency which is variable between 40 to 60 KHz and is used to control the voltage at the center tap 54 to the primary winding P of the high voltage transformer 48 (Figure 2). The value of the output signal CT-DRIVE is changed by the micro-controller U4 in response tG a stored.~igh voltage algorithm. This output signal C~-DRIVE is fed to the gate of a P-channel FET Q4, which is preferably an International Rectifier type IRF9530, via a driver integrated circuit V16 and a resistor R55. The driver integrated circui~ U16 is preferably a Motorola type ULN2003A. The drain of the FET Q4 is fed to the conventional high side dri~e flyback switching regulator 62. The integrated circuit U17 is selected by the chip select pin P2.5/HLD ~siqnal CS1~ of the micro-controller U4.
The switching regulator 62 includes a 150 uh choke L1 having its one end connected to the drain of the FE~
~- Q4. The ~ource of the FET Q4 is connected to the 6upply potential of ~24 VDC. The cathode of a flyback diode D7 is also connected to the drain of the FET Q4. The anode of the diode D7 is connect d to a gro~md potential. A
470 uF capacitor C19 is connected betw,een the other end of the choke Ll and the ground potential. A voltage divider formed by resistors R29 and R45 is also coupled between the other end of the choke Ll and the ground potential. The output of the switching regulator is taken from the upper end of the resistor R29. The -~unction of the resistor R29 and R45 provides the regulator feedback signal V-CT, which varies between 0 to 5 VDC corresponding to the 0 to 30 VDC center tap voltage available to the primary winding of the high voltage transformer 4B. This signal V-CT is ~ed to pin P0.5/AC~5 of the micro-controller U4.
The first switching driver circuit 4~ includes a FET
Q2, which is preferably an International Rectifier type IRF530. The second switching driver circuit 46 also includes a FET Q1, which is preferably an International Rectifier type IRF530. The F~T Q2 ha~ its gate connected to receive the first drive signal DRIVE1 from pin :: ' :' ~ . . ' ' ~ ~ :
4,538,231 4,891,743 -4,587,605 5,019,996 4,630,220 5,107,438 . . .
~ ~ '3~
In U.S. Patent No. 4,409,635 to Kraus issued on October 11, 1983, there is disclosed an electrical power -- system which includes a microprocessor-based control unit for maintaining power output and performing control functions. The control unit is comprised of a micro-processor, digital comparator, read-on].y memory, output means for producing control signals, and a feedback circuit which implements the locking ~eature. The control unit conducts a series of self-test routines which evaluate the opera~ing condition of the system components. The control unit utilizes a sequential key word kechnique to provide a means of failure detection.
In U.S. Patent No. 4,472,781 to ~iller issued on September 18, 19~4, there is disclosed a power supply system for electronic postage meters which includes a switching type regulated power supply for generating switched regulated D.C. output voltages. The postage meter has a control module which includes a micro~
processor and control circuits.
In U.S. Patent No. 4,891,743 to May et al. issued on January 2, 1~2, there is disclosed a control system for an industrial inverting type power supply which provides _5- CASE 751 both operational control and a diagnostic capability for the power supply. The control system includes a -- controller 1 which is interfaced to an ~nverter type industrial power supply 2 and to an external system 3 through an input isolation circuit 4 and an output isolation circuit 5. The controller also inter~aces to a locàl display 20 and a remote display 21 via respective RS-485 serial communica~ion lin~s 22 and 23. The dis-plays 20 and 21 are used to display certain operational and diagnostic information. Each of the displays contains switches and controls for operator input and a display screen for displaying operational and diagnostic information to the operator. The controller 1 also communicates with a local terminal 25 and a remote terminal 26 each being a personal computer system. The controller is comprised of a microprocessor 101 having a system bus 101 connected to a ROM 105, a RAM 106, and EEPROM 107.
Further, there are known in the prior art of electrical power supplies for generating high magnitude electrostatic potential for use in industrial electro-static coating systems as illustrated in U.S. Patent Nos.
4,187,527; 4,485,427; and 4,745,520 all owned by the assignee of the present invention. In '527 patent, there 3 ~ ~
is described a system 10 for electrostatic deposition o~
a coating on an article from a charging device which includes a shorting device 36 for reducing the potential across the output terminals 32 and 34 of a high voltage circuit 30 in response to control signals ~rom ~ control circuit 40. The control circuit includes a slope-detecting circuit 44 responsive to a sensed current to detect ~oo-rapid changes therein indicating of possible high voltage arcing. The control circuit also includes an automatic ranging circuit which compares a sampled signal related to the actual current through a sensi.ng resistor with a signal related to a predatermined multiple of the instantaneous current through the sensing resistor.
lS In the '427 patent, there is shown a power supply for a coating material dispenser for dispensing electro~
statically charged particles of coating material which includes an electrostatic potential generator having a "fold-back" voltage-current characteristic including a reduced voltage-reduced current curve region wherein the energy available at the dispenser is less than that necessary for spark ignition. In the '520 patent, there is illustrated a high magnitude electrostatic potential supply, an electrostatic potential utilization device, 3 ~
and a coupling device connecting the electrostatic potential supply to the utilization device. ~he coupling -- device consists essentially o~ a conductor having sub- -stantially no distributed capacitance and substantially no distributed resistance.
~- ~ r However, none of the prior art discussed above teach a high voltage power supply for use in electrostatically-aided coating material system equipment for dispensing electrostatically charged particles of coating material like that of the pxesent invention which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. Further, a personal computer is connectible to the controller for a communication link so as to facilitate engineering development and service.
The.present invention represents significant improvements over the '527, '427, and '520 patents, which are hereby incorpo~ated by reference.
SUMMARY OF THE INVEN?ION
Accordingly, it is a general object of the present invention t~ provide an improved high voltage power , : : ; . . . , ~
i 8 supply for use in electrostatically-aided coating material application equipment for dispensi~g electro-_. statically charged particles of coating material whichincludes a control ~odule having a controller operated under a stored program to perform all control, safety and oper~ting diagnostics.
~ ~ r ~ -~
It is an object of the present invention to provide an improved high voltage power supply for dispen~ing electrostatically charged particles of coating material which is implemented with a reduced number of discrete components and occupying less printed circuit board space than has been traditionally available.
It is another object of the present invention to provide an improved high voltage power supply for dispensing electrostatically charged particles of coating material which includes a personal computer connectible to a controller over a communication link so as to alter all control and safety diagnostic parameters as well as retrieving stored diagnostic in~ormation.
- . , .. , ~
It is still another object oP the present i-nvention to provide an improved high voltage power supply for dis-pensing electrostatically charged particles o~ coating ~aterial which includes a non-volatile me~ory ~or ~toring current parameter 6etting5, normail ~urn-on table values, fault turn-on table values, and a constants table.
, . . .
It is yet still anothier.object o~ the present invention to provide an improved high voltage power supply for dispensing electrostatically charged particles ~0 of coating material which is formed of a con~rol module having a controller, a high voltage module for generating a high voltage output, and a programmable bandpa~s filter coupled to the high voltage module ~or supplying current and voltage feedbacX signals to the controller.
It is still yet another object of the present invention to provide improved high voltage power supply for dispensing electrostatically charged particles of coating material which includes a controller ~or generating first and second complementary drive signals ~-having a programmable dead space time therebetween. ~-.. . .............. . .
~' ' ' ' ~ . ' 2.~.~.9~v~
-lO- CASE 751 In accordance with a preferred embodiment of the present invention, there is provided a high voltage power -- supply for use in electrostatically-aided coating material application equipment for di~spensing electro-statically charged particles of coating material which includes an electrostatic potential utilization device, ~ ~ r a high voltage module, a high voltage cable ~or coupling the hig~ voltage module to the utiliz~tion device, a low voltage D.C. power source, and a control module. The high voltage module includes a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output. The control module includes a switching type regulator which is responsive to the D.C.
lS power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver cirGuits for switching the regulated operating voltage across the primary winding.
-:
The control module also includes a controller for generating first and second drive signals for the first and second switching driver circuits. A non-volatile memory i5 provided ~or storing current parameter settinqs, normal turn-on table values, fault turn-on table values, and a constants table. The controller is Y ~
:, .
adapted to perform safety an~ operatiing diagnostic through a stored program based upon the settings and _ .values obtained from the non-volatile memory.
BRIEF DESCRIPTION OF THE D~WINGS
.
These and other objects and adivantages of the present invention will become more fully apparent ~ro~
the following detailed description when read in con-junction with the accompanying drawings with like reference numerals indicating corresponding parts throughout, wherein:
Figure 1 is a simplified block diagram of a micro-controlled based high voltage power supply, constructed in accordance with the principles of the present invention;
Figure 2 i5 a more detailed block diagram of the high voltage power supply of Figure 1;
Figure 3 shows the waveforms ~a3 and (h) of the complementary drive signals appearing at the outputs of the first and second switching dri~er circuits of Figure 2;
?~ i 8 Figure 4 is a pictorial representation of a front . panel used in the high voltage power supply of Fi~ures 1 ~- and 2;
Figures 5(a)-5(g) are detailed sc:hematic circuit diagrams showing suitable circuitry for use in certain ones of the blocks of Figure 2;
Figure 6 illustrates an output potential-current characteristic of the present high voltage power supply;
Figure 7 is a graphical representation o~` a first menu, illustrating Tables 1 through 3;
-~ . - ' .
::: , :
Figure 8 is a graphical representation of a second `~
menu, illustrating Table 4; and Figure 9 is a graphical representation oP a third menu, illustrating Table 5;
.
DESCRIPTION OF THE PREFERRED_EMBODIMENT :~
Referring now in detail to the drawings, there is shown in Figure 1 a block diagram o~ a micro-controller based high voltage power supply 10 for use in J" 'LiC3 ~
electrostatically-aided coating material application equipment for dispensing electrostatically charged . particles of coating material, constructed in accordance with the principles o~ the present invention. The micro-controller based high voltage power supply is used tosupply up to 100,000 D.C. at 300 uA so as to assist in the atomization and transfer efficiencies of the electro-static coating application equipment. The high voltage power supply 10 is comprised o~ a control module 12, a high voltage module 14, and an electrostatic potential utilization device 16 such as a coating atomizer.
A low voltage power supply 18 is provided to produce a relatively low voltage of +24 volts D.C. which is connected to the control module 12 via line 20. The high voltage module 14 includes a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output. The high voltage module has an input terminal 22 which is connected to the control module 12 by a low voltage cable 26. The high voltage module also includes an output terminal 24 for supplying the high voltage output to the coating atomi~er 16 via a high voltage-cable 28. The coating atomizer 16 serves to produce atomized particles of a coating material, such as liquid paint or powder, which will be attracted toward and deposited electrostatically upon an article or target -- 30 to be coated. The arti~le 30 is typically moved past the coating atomizer 16 on a conveyor (not shown).
~ ~ r ~he control module 12 is controlled externally by input~oùtput (I/O) devices connectible via line 32 so as to perform control of the entire coating process. A
personal computer may optionally be provided for communication with the control module 12 via a serial da~a link 36. The personal computer is especially use~ul by appropriate personnel in an engineering development environment so as to easily alter many different control, safety and operating diagnostic parameters in order to adapt the power supply for a particular application.
In Figure 2, there is shown a more detailed block diagram of the power supply 10 of Figure 1. The control ~odule 12 includes a micro-controller 38 which is preferably an Intel type AN87C196KR. The micro-controller 38 generates two complementary drive signals on lines 40 and 42, which may be programmable with a "dead space" ~small period of time when nei~her signal is active) during the cross-over portions thereof. These ," . ., ., ~ . . , . ~ ~, : , . , 2 ~
drive signals are illus~rated in Figures 3(a) and 3(b), respectively. The control module 12 includes a first switching driver circuit 44 connected to the line 40 and ; ~
a second switching driver circuit 46 connected to the line 42. The hig~ voltage module 14 includes the high voltage transformer 48 having a primary winding P and a secondary winding S. The primary winding P has a first end 50, a second end 52, and a center tap 54. The first end 50 is connected to the output of the first switching driver circuit 44 via line 56, and the second end 52 is connected to the output of the second switching driver circuit 46 via line 58.
The control module 12 ~urther includes a program-mable frequency/pulse wid~h generator 60 and a switching inverter type regulator 62. The pulse width generator 60 has its input connected to the micro-controller 38 via line 64 and its output connected via line 65 to the input of the switching regulator 62. The output of the switch-ing regulator 62 provides a regulated operating voltage which is fed to the center tap 54 of the primary winding P via line 66. The center tap voltage is regulated by a regulator feedback signal on line 68 from the switching regulator, which is generated by a resistive voltage divider circuit located in the switching regulator. This - ) regulator feedback signal is sent to the micro-controller 38.
A feedback voltage on line 70 is generated by the high voltage module 14, which represents an output current signal. This output current feedback signal is generat-ed via a resistance connected in series with the xeturn path in the high voltage multiplier circuit of the high voltage module to ground. This current feedback voltage is fed to a programmable bandpass filter 72 and then to the micro-controller 38 via a bu~fer 74. This current feedback voltage representing output current is used by the micro-controller 38 to display the value and to perform safety dia~nostics as will be descri~ed here-inafter. Another feedback voltage on line 76 is also generated by the high voltage module 14 and represents an output XV signal which is used to display the value and to perform the closed-loop control algorithms necessary to regulate the center-tap voltage for a stable high voltage output at the output terminal 24. This fPedback volta~e is fed to the micro-controller 38 via a buffer 77.
Digital I/O circuits 78 and analog I/O circuits 80 are coupled between the micro-controller and a user block -- 82 for supplying status signals to the user and for receiving external control signals to the micro-controller. A display decoder/driver 84 is used to inter~ace KV and I displays 86a and 86b with the micro-~, ~ r controller. Lamp driver~ 88 are used to interface the micro-controller with front panel lamps 90a-9Oe. A
parallel-to-serial converter circuit 91 is used to inter~ace the micro-controller with the front panel swit~hes 92a-92h. A non-volatile RAM 94 is provided for storing al} of the operating and diagnostic information which is controlled by the micro-controller via line 96.
A digital expansion port 98 is used to provide a communi-cation link via lines lOo and 102 when special controlinterfaces are required. A serial communication por~ 104 is used to interface the micro-controller via lines 106 and 108 with the personal computer 3~.
A pictorial representation of a front panel 110 used in the power supply of Figures 1 and 2 is illustrated in Figure 4. Referring now to Figures 2 and 4, the output KV display 86a is a 3-digit display for indicating the actual voltage for the desired set voltage which is between 20 to 100 KV. This setting can be changed by de-'`~` J~ 'J7 ~_7 ~3 -18- ~ASE 751 pressing the ADJUST-UP pushbutton s2a or the ADJUST-DOWN
_. pushbutton 92b. When the pushbutton s2a is depre~sed, the output XV display 86a will have its decimal point lit and~will display the stored value which can be ~hen incremented continuously. When the puGhbutton 92b is depressed, the output XV di~play 86a will indicate the 6tored val~e which can be then decrement~d continuously.
Once the pushbutton 92a or 92b is relea~,ed, the present set value of the desired voltage will be stored in the non-volatile RAM 94. A momentary ~V ON pushbutton 9~c i.s depressed so as to supply the high voltage output ~rom th~ high voltage module 14 to the coating atomizer 16.
A ~omentary HV OFF pushbutton 92d is depressed 50 as to disconnect the high voltage from the high voltage module to the coating atomizer.
The output CURRENT display 86b is a 3-digit display ~or indicating the actual current or the desired set current which is between 50 to 1000 uA. When the CURRENT
LIMIT pushbutton 92e (located under a removable panel door 112) is depressed, this allows the operator to set the maximum current whi~h the power supply 10 will deliver. Similarly, when the pushbutton g2a i8 depressed, the output CURRENT display 86h wîll have its decimal point lit and will display the stored value which . ::: ~ : : : :
: ~ .~ , , -.
: ~ ) can be then incremented continuously. When the pushbutton 92b is depressed, the output CURRENT display -- 86b will indicate the stored value w]hich can be then decremented continuously. Once the pushbutton 92a or 92b is released, the present value of the~ desired current will al~o be stored in the non-volatile RAM 94.
~I ~ t As can be seen from Figure 6, there is shown the output high potential-output current characteristic which the present power supply seeks to provide referred to as a so-called "fold-back" characteristic. That is, this characteristic is where the output vol~age/output current varies generally linearly along an increasing current-decr~asing potential line 610. This is achieved by setting a SLOPE reduction point 612. It will be noted that the output voltage decreases along the line 610 when the current increases beyond this SLOPE reduction point 612. The value of the CURRENT LINIT setting will always be the final cut-off point 614 for the curren~. At this point 614 (intersection of the horizontal 20 KV line and the vertical current limit line~, the overload condition will be reached and the high voltage will be disabled or switched to zero and the F~ULT lamp 90c will be turned on~
~, ~ ` ~'3~ 9 ~ ~
Again, this SLOPE reduction point 612 can be set by the operator by depressing the SLOPE pushbutton 92f and _- either the pushbutton 92a or 92b. When the pushbutton 92a is depressed, the output KV display 96a will be blànked and the stored value of the SLOPE reduction setting will be displayed which can be then incremented ~1 ~ r continuously. When the pushbutton s2b is depressed, the stored ~alue of the SLOPE setting will be indicated on the display 86a and the value thereof can be then decre-mented continuously. When the pushbutton 92a or 92b isreleased, the present value of the SLOPE setting will be likewise stored in the non-volatile RAM 94.
The CORONA SENSE setting has a stored value between 1 and 100, which corresponds to an output voltage between 0 to 5 volts of the bandpass filter 72. The stored value is a measure of the chaos in the operating environment of the high voltage power supply 10. This chaos represents the presence of corona on the high voltage cable 28 and that corona is a precursor to a sparX. ~hen the corona sense is within 80% of the setting, th~ CORONA SENSE lamp 90e will be flashing at a rate o~ approximately one hertz. When the corona sense is within 90% of the setting, the -lamp 90e will be flashing at approximately two hertz. When the corona se~se reaches the setting, ,. . . . .
7.~ 9~3~ _) -21- ~ASE 751 the high voltage will be disabled and the FAULT la~p 9Oc -- and the CORONA SENSE amp 90e will both be lit.
The corona sense value is ~et by the operator by ~ ~ s depres~ing ~he CORONA pushbutton 92g and either the pushbutton 92a or 92b. When the pushbutton 92a is depressed, ~he output KV display 86a will again be blanked and the stored value of the corona ~ense setting ~ ~
will be displayed which can be then incrementecl con- ~ -. ~
tinuously. When the pushbutton 92b is depressed, the stored value of the corona sense setting will be indicated on the display 86a and the value thereof can be then decremented continuously. When the pushbutton 92a or 92b is released, the present value of CORONA SENSE
setting will also be stored in the non-volatile RAM 94.
While th~ various blocks 38, 44, 46, 60, 62, 84-92, 94 and 98 ~ay take on various forms, suitable circuitry therefor is illustrated in Figur~s 5~a) through 5(g).
EYen though these schematics are believed to be self~
explanatory to those skilled in the art in view of the foregoing description, a brief de~cription of the opera-tion of several of these blocks is believed to be in order.
~f~,~3 ~ 8 ; , ,, Referring now to Figures 2 and 5(a)-5(g), there is _- shown an integrated circuit U4 which corresponds to the micro-controller 38 (Figure 2) and is preferably an Intel type AN87C196KR. The pin numbers illustrated in the ~ :
drawings are those applicable when this particular integrated circuit i5 employed for this purpose. This convention will be used when referring to the various integrated circuits described throughout this description of the preferred embodiment. However, it should be clearly understood that other integrated circuits could be employed ~or these purposes for which the various integrated circuits described herein are used. :
The micro-controller U4 has three high speed serial ports P6.7/SD1 (signal DO), P6.~/SCl (signal SK), and P6.5/SD0 (signal DI) which are used to load information into two digital pulse width modulator integrated circuits U13 and U14. The integrated circuits U13 and U17 are preferably a Harris type CDP68HC68WlE, which are used to modulate the 8 MHz clock output from pin P2.7/CLKOUT of the ~icro-controller U4 in order to supply a variable frequency and duty output sisnal on its respective pin 7. The output signal CLX-IN-I on pin 7 of Ul3 has a frequency which is variable between 5 KHz and : ~, ... . ~ .,: ,. ~ : , : ... , :
2 ~ `9 3 ~
. ~
100 gHz corresponding to a center frequency of the corona programmable bandpass filter U18 (72 of Figure 2) of -- '0.1 KHz to 2 KHz. The integrated circu.it U18 is prefer-ably a National typa LMFlOOCN which rec:eives the output signal CLK-IN-I on its pin CLKa. The integrated circuit U13 is selected by the chip select pin 1'2.3/INTB (signal CS3) of the micro-controller U4.
Similarly, the output signal CT-DRIVE on pin 7 of U17 has a frequency which is variable between 40 to 60 KHz and is used to control the voltage at the center tap 54 to the primary winding P of the high voltage transformer 48 (Figure 2). The value of the output signal CT-DRIVE is changed by the micro-controller U4 in response tG a stored.~igh voltage algorithm. This output signal C~-DRIVE is fed to the gate of a P-channel FET Q4, which is preferably an International Rectifier type IRF9530, via a driver integrated circuit V16 and a resistor R55. The driver integrated circui~ U16 is preferably a Motorola type ULN2003A. The drain of the FET Q4 is fed to the conventional high side dri~e flyback switching regulator 62. The integrated circuit U17 is selected by the chip select pin P2.5/HLD ~siqnal CS1~ of the micro-controller U4.
The switching regulator 62 includes a 150 uh choke L1 having its one end connected to the drain of the FE~
~- Q4. The ~ource of the FET Q4 is connected to the 6upply potential of ~24 VDC. The cathode of a flyback diode D7 is also connected to the drain of the FET Q4. The anode of the diode D7 is connect d to a gro~md potential. A
470 uF capacitor C19 is connected betw,een the other end of the choke Ll and the ground potential. A voltage divider formed by resistors R29 and R45 is also coupled between the other end of the choke Ll and the ground potential. The output of the switching regulator is taken from the upper end of the resistor R29. The -~unction of the resistor R29 and R45 provides the regulator feedback signal V-CT, which varies between 0 to 5 VDC corresponding to the 0 to 30 VDC center tap voltage available to the primary winding of the high voltage transformer 4B. This signal V-CT is ~ed to pin P0.5/AC~5 of the micro-controller U4.
The first switching driver circuit 4~ includes a FET
Q2, which is preferably an International Rectifier type IRF530. The second switching driver circuit 46 also includes a FET Q1, which is preferably an International Rectifier type IRF530. The F~T Q2 ha~ its gate connected to receive the first drive signal DRIVE1 from pin :: ' :' ~ . . ' ' ~ ~ :
6.0/EPA8 of the micro-controller U4, and the FET Q1 has its gate connected to receive the second drive signal .DRIVE2 from pin P6.1/EPA9. The ends 50 and 52 of the primary winding of the transformer 48 (Figure 2) are coupled to the respective drains of the FETS Q2 and Q1.
~ ':
~ ~ r :
Th-e micro-controller U4 receives a voltage signal KV INPUT on pin P0.0/ACH0 which has a value between 1 to 5 VDC representing the high voltage output of 20 to 100 XV, a signal I-FB on pin P0.1/ACH1 which has a value between 0 to 5 VDC representing o to 1,000 uA of current from the high voltage p~wer supply, a signal KV-Fs on pin P0.3/ACH2 which has a value between 0 to 2.5 VDC
representing 0 to 100 XV output from the high voltage power supply, and a signal CORONA-FB which has a value between 0 to 5 VDC representing the output o~ the corona sense bandpass filter U18. The voltage signal KV INPUT
is scaled so that 1 VDC equals 20 KV. The micro-controller U4 will respond to the value changes of this signal by adjusting the high voltage output. The signal I-FB is referred to as "pack return" current, which is a measure of the current flowing ~rom the coating atomizer to ground and then returning to the low side o~ the power supply. The signal I FB is scaled 50 that 1 VDC equals 200 uA. The signal KV-FB is a measure o~ the high voltage output and is monitored by the micro-controller U4 and is controlled 60 as to determine the desired high -- ~voltage output. The signal CORONA-FB is a peaX detected signal from the bandpass filter U18 whose amplitude is ~ompared with a corona sense safety setting.
~ c Thë micro-controller U4 also provides ~ power lamp signal on pin P4.4 for turning on POWER lamp 90f whe~ the power switch 92h is activated, a hv-on lamp signal on pin P4.5 for turning on the ~V-ON lamp 90a, a hv-off lamp signal on pin P4.6 for turning on the HV-OFF lamp 90b, a fault lamp signal on pin P4.7 for turning on the FAULT
lamp 90c whenevex the current feedback signal on pin ACH1 exceeds the value set by khe current limit, a hv ready lamp siqnal on pin P5.0 for turning on the HV READY lamp 90d, and a oorona sense lamp signal on pin P5.1 for turning on the CORONA SENSE lamp 90e in response to the relationship of ~he corona feedback signal on pin ACH6 and the stored value of CORONA via lamp driver integrated circuit U15. The integrated circuit U15 (84 of ~igure 2) is preferably a Motorola type ULN2003A.
The hig~ speed serial I/O ports (P6.7, P6.6 and P6.5) are also used to drive the non-volatile memory 94.
~ t~ ~t~
,) ~27- -CASE 751 The non~volatile memory is an electr:ical}y erasable -- programmable read-only memory (EEPROM) integrated circuit Ull, w~ich is preferably a National type NMC9346EN. The integrated circuit Ull is selected by the chip select pins P2.5/HLD (signal CSl) and P2.~/IN'r ~ignal CS2).
The integrated circuit ~11 has the capac:ity to store 64 16-bit words. The EEPRO~ Ull is used fox the storage of dat~ that is collected during ~el-diagno~tics and~or fault conditions as well as set-up parameters which will be changed fro~ time to time as the power supply is bein~
used. The values stored in the EEPROM U11 are the d~sired high voltage output (KV SET), the current limit setting (I LIMIT SET), the tstlope setting (SLOPE SET) and corona sense setting ~CORONA SET) as shown in Table 1 of the menu of Figure 7.
In addition, the values for normal turn-on in Table 2 of the menu of Figure 7 is also stored. These values include "ONl'IME," "CORONA," and "di/dt.'i The "ONTIME' value is the amount of time ~or the voltage to ramp up to 20 KV. Assuming that the final high voltage output is to be 100 KV, the "ONTI~E" value for each of the five 20 RV
increments of the high voltage output, i.e., ONTINE (0), ONTIME (1), etc., can be separately selected by the u6er.
For example, the value 60 in the ONTIME (0) is multiplied :
3~ ) by 10 ms so as to determine the actual time. In sther words, the value 60 means that vol~age is to ramp up to _- 20 KV in 600 ms or .6 sec. in the first 20 KV increment.
.
The "CORONA" ~alue is a relative number be ween o to ~ c r 100 with 0 being the most sensitive. This "CORONA" value can be Iikewise separately selected by the user for each of the five 20 KV increments of the high voltage output.
The "ditdt" value is the maximum rate of rise of the output current which is allowed during each 20 KV
increment of the high voltage output. These values are given in units of uA/sec. The micro-controller evaluates the rate of rise every 10 ms. Thus, the "di/dt" of 4000 uA/sec is equal to 40 uA/10 ms. This means that if there is a 40 uA rise in the current during a 10 us time period an overload would be indicated. Further, the values for the fault turn-on after a "soft" fault condition in Table 3 of the menu of Figure 6 are also stored. These values are identical in function to the ones in TabIe 2.
In Figure 8, there is shown in Table 4 of khe menu tha values stored after the voltage turn-on has been completed. ~hese are also identical in function to the ones in Table 2 of Figure 6. However, it should ~e noted 8, that the values for "di/dt" are set lower than the ones ~ ~n Table 2 since t~e capacitances are charged at steady-state.
- ~ c r In Figure 9, there i8 ~hown in Table 5 o~ the menu ~he constant values to be ~tored in the EEPROM Ull.
These constant values include a ~undamental drive frequency FUND FREQ and the fundamental P~M value FUND PWM. The value of FUNV FREQ is multiplied by .1 KHz so as to obtain the actual drivs frequency. For example, the value of 140 equals 14 XHz. The value of FUND PWM is the amount of delay time (dead space) between the two complementary drive signals DRIVEl and DRIVE2, as shown in Figure 3. This value is settable between 128 to 256.
This value i~ multiplied by .025 uS so as to determine the amount of dead space. For exampl~, 245 e~uals 6.125 uS. The delay incxeases efficiency and lowers th~
amount of heat dissipation Pro~ the drive transistors Q1 and Q2. The other constant value includes overload de~
lay, soft fault delay, so~t fault retries, hard fault retries, and the number of hours that the high voltage output has been on as well as the others listed in Table 5.
` ~ q ~ 3, ~
_30_ CASE 751 The personal computer communicates with the micro-controllex U4 by an RS/232 port which is used during en-~gineering development and service. The personal computer allows the power supply para~etexs, real time values, and 5setting to be easily viewed and/or changed. In par-ticular, all of the table parameters in the menus of Figures 7 through 9 are sent and received as 15-bit ..
binary words.
A ~ore detailed schematic circuit diagram of the 10high voltage module 14 of Figure 2 is shown in Figure 3a of U.S. Patent No. 4,74S,520, which is hereby incorporated by re~erence. There is shown in Figure 3a of the '520 patent a high vol~age transformer 72 and a high potential rectifier and multiplier 110. ~urther, 15there is shown the resistor 124 connected betwee~ grou~d and ihe terminal 120 for providing a voltage signal which corresponds to the multiplier 110 output current. This corresponds to the current feedback signal on the line 70 of Figure 2. Further, there is provided in the '520 20patent the series of resistors 130, 132 and 124 coupled between the terminals 114 a~d 120 so as to provide a voltage signal which corresponds to the output voltage.
This corresponds to the voltage feedback signal on the line 76 of Figure 2.
, ,.
In operation, the normal high voltage turn-on -- process is achieved through the micro-controller U4 by initially energizing the two complementary switching FET
Q1 and Q2 connected to the ends of the primary winding P
5 of the high voltage ~ransformer 48. Then, the FET Q4 connected between the pulse width modulator integrator ~ ~ r circult U17 and the switching regulator 62 will be energized so as to control the D.C. voltage level at the center tap 54 of the primary winding P. This D.C.
voltage level is alternately switched through the two halves of the primary winding P by the two FETS Q1 and Q2 under the control of the micro-controller V4. As a result, there is induced voltage variations in the secondary winding S of the high voltage transformer 48.
Finally, the high voltage output will be ramped up to the final desired value by increasing the center tap voltage.
The center tap voltage is controlled by modulation of the width of the pulses at the gate of the FET Q4.
As the high voltage i5 ramped up, the rate of change of the "pack return" (current feedback) is compared against the stored normal turn-on values o~ Table 2 in Figure 7. This current feedback is also compared with the present setting o~ the current limit value in Table 1 of Figure 7. Thus, the high voltage turn-on curve is dependent upon the value of the current feedback as well ~- 'as being ti~e dependent.
The micro-co~troller U4 will fetch the fundamental ,. . . .
drive ~requency and the PWM values from the stored constants in Table 5 o~ Figure 9 for the first and second drive signals DRIVE1 and DRIVE2. Then, the micro-controller U4 will activate the signal CT-DRIVE at the fundam6ntal frequency and minimum PWM value. The micro-controller will increase the PWM value until the desiredhigh voltage output is reached. During this turn-on process, the micro-controller will monitor all of the safety circuits (i.e., the current feedback signal I-FB
and corona sense signal CORONA). The high voltage will be ramped up in accordance with the stored turn-on values. If the current ~eedback or the corona sense values exceed the respective stored values, the power supply will overload and disconnect the hiyh voltage output, and the FAULT lamp 90c will be turned on. On the other hand, once the operatlng value of the current KV SET (Table l) has been reached, this will be the ready-~tate condition.
_33_ CASE 751 It should be understood that an overload condition will occur when any of the safety circuits determine that -- the preset value has been exceeded. I~ it i6 determined that the overload is a ~soft fault" where the high voitage output is being reduced in response to the SLOPE
setting and has encountered the 20 KV minimum voltage or ~ I ~ t the corona sense limit has been exceeded, the power supply will attempt to recover from the "soft fault" a predetermined number of times as stored in the constants table. However, if the overload is a "hard fault" where the current limit setting has been exceeded or the di/dt value has been exceeded, no recovery will be attempted.
After the steady-state value of the high voltage has been reached, this period is referred to as "HIG~ VOLTAGE
lS ON." The micro-controller will perform the algorithm stored in the non-volatile memory so as to optimize the efficiency of the high voltage moduleO In particular, the micro-controller will sweep the fundamental frequency of the switching regulator so as to obtain the lowest value of the center tap voltage V-CT. The range of the allowable frequency and the increment of change are determined by the constants in Table 5. The micro-controller w~ll monitor the value HV-ON ~OURS and will attempt to optimize the value of the voltage V-CT every ~ 3 ~3 ~ 8 .~5 hours. During the normal "HV ON" interval, the current feedback will be changed routinely in response to the passage of the target or article to be coated and the triggering of the coating makerial. The power supply will attempt to maintain the desired high voltage output at the out,put terminal 24 as the current feedback chang~s by ad~usting the PWM value.
The high voltage power supply of the present invention has the following advantages over the pr:ior art:
(1) It uses a controller operated under a stored program to perform all control, safety and operating diagnostics;
(2) It provides a large amount of versatility and ~15 adaptability to changes in design parameters or different applications by changes in software only;
(3) It provides a non-volatile memory for storage of current setting parameters, turn on table values, and constants for use by the controller; and (4) It provides a personal computer connectible to the controller so as to easily alter the operation of the ~ power supply or retrieve diagnostic in~ormation.
From the foregoing detailed description, it can thus 1~ t 1- .
be seen that the present invention provides an impro~ed high voltage power supply for use in electxostatically~
aided coating material application equipment :Eor dispensing electrostatically charged particles of coating material which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. A
non-volatile memory is provided for storing current para-meter settings, turn-on table values, and a constants ~able. A personal computer is connectible to the controller by a communication li~k to permit changing of the values stored in the non-volatile memory so as to facilitate engineering development and servi~e.
While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for 3,~
-36~ CASE 751 elements thereof without departing from the true scope of the invention. In addition, many modifications may be ~~ made to adapt a particular situation or material to the teachings of the invention without departing from the central scope thereof. Therefore, it .is intended that this invention not be limited to the particular embodi-ment disc~o~edfas the best mode contemplated ~or carrying out the. invention, but that the invention will include all embodiments falling within the scope of the appended claims.
~ ':
~ ~ r :
Th-e micro-controller U4 receives a voltage signal KV INPUT on pin P0.0/ACH0 which has a value between 1 to 5 VDC representing the high voltage output of 20 to 100 XV, a signal I-FB on pin P0.1/ACH1 which has a value between 0 to 5 VDC representing o to 1,000 uA of current from the high voltage p~wer supply, a signal KV-Fs on pin P0.3/ACH2 which has a value between 0 to 2.5 VDC
representing 0 to 100 XV output from the high voltage power supply, and a signal CORONA-FB which has a value between 0 to 5 VDC representing the output o~ the corona sense bandpass filter U18. The voltage signal KV INPUT
is scaled so that 1 VDC equals 20 KV. The micro-controller U4 will respond to the value changes of this signal by adjusting the high voltage output. The signal I-FB is referred to as "pack return" current, which is a measure of the current flowing ~rom the coating atomizer to ground and then returning to the low side o~ the power supply. The signal I FB is scaled 50 that 1 VDC equals 200 uA. The signal KV-FB is a measure o~ the high voltage output and is monitored by the micro-controller U4 and is controlled 60 as to determine the desired high -- ~voltage output. The signal CORONA-FB is a peaX detected signal from the bandpass filter U18 whose amplitude is ~ompared with a corona sense safety setting.
~ c Thë micro-controller U4 also provides ~ power lamp signal on pin P4.4 for turning on POWER lamp 90f whe~ the power switch 92h is activated, a hv-on lamp signal on pin P4.5 for turning on the ~V-ON lamp 90a, a hv-off lamp signal on pin P4.6 for turning on the HV-OFF lamp 90b, a fault lamp signal on pin P4.7 for turning on the FAULT
lamp 90c whenevex the current feedback signal on pin ACH1 exceeds the value set by khe current limit, a hv ready lamp siqnal on pin P5.0 for turning on the HV READY lamp 90d, and a oorona sense lamp signal on pin P5.1 for turning on the CORONA SENSE lamp 90e in response to the relationship of ~he corona feedback signal on pin ACH6 and the stored value of CORONA via lamp driver integrated circuit U15. The integrated circuit U15 (84 of ~igure 2) is preferably a Motorola type ULN2003A.
The hig~ speed serial I/O ports (P6.7, P6.6 and P6.5) are also used to drive the non-volatile memory 94.
~ t~ ~t~
,) ~27- -CASE 751 The non~volatile memory is an electr:ical}y erasable -- programmable read-only memory (EEPROM) integrated circuit Ull, w~ich is preferably a National type NMC9346EN. The integrated circuit Ull is selected by the chip select pins P2.5/HLD (signal CSl) and P2.~/IN'r ~ignal CS2).
The integrated circuit ~11 has the capac:ity to store 64 16-bit words. The EEPRO~ Ull is used fox the storage of dat~ that is collected during ~el-diagno~tics and~or fault conditions as well as set-up parameters which will be changed fro~ time to time as the power supply is bein~
used. The values stored in the EEPROM U11 are the d~sired high voltage output (KV SET), the current limit setting (I LIMIT SET), the tstlope setting (SLOPE SET) and corona sense setting ~CORONA SET) as shown in Table 1 of the menu of Figure 7.
In addition, the values for normal turn-on in Table 2 of the menu of Figure 7 is also stored. These values include "ONl'IME," "CORONA," and "di/dt.'i The "ONTIME' value is the amount of time ~or the voltage to ramp up to 20 KV. Assuming that the final high voltage output is to be 100 KV, the "ONTI~E" value for each of the five 20 RV
increments of the high voltage output, i.e., ONTINE (0), ONTIME (1), etc., can be separately selected by the u6er.
For example, the value 60 in the ONTIME (0) is multiplied :
3~ ) by 10 ms so as to determine the actual time. In sther words, the value 60 means that vol~age is to ramp up to _- 20 KV in 600 ms or .6 sec. in the first 20 KV increment.
.
The "CORONA" ~alue is a relative number be ween o to ~ c r 100 with 0 being the most sensitive. This "CORONA" value can be Iikewise separately selected by the user for each of the five 20 KV increments of the high voltage output.
The "ditdt" value is the maximum rate of rise of the output current which is allowed during each 20 KV
increment of the high voltage output. These values are given in units of uA/sec. The micro-controller evaluates the rate of rise every 10 ms. Thus, the "di/dt" of 4000 uA/sec is equal to 40 uA/10 ms. This means that if there is a 40 uA rise in the current during a 10 us time period an overload would be indicated. Further, the values for the fault turn-on after a "soft" fault condition in Table 3 of the menu of Figure 6 are also stored. These values are identical in function to the ones in TabIe 2.
In Figure 8, there is shown in Table 4 of khe menu tha values stored after the voltage turn-on has been completed. ~hese are also identical in function to the ones in Table 2 of Figure 6. However, it should ~e noted 8, that the values for "di/dt" are set lower than the ones ~ ~n Table 2 since t~e capacitances are charged at steady-state.
- ~ c r In Figure 9, there i8 ~hown in Table 5 o~ the menu ~he constant values to be ~tored in the EEPROM Ull.
These constant values include a ~undamental drive frequency FUND FREQ and the fundamental P~M value FUND PWM. The value of FUNV FREQ is multiplied by .1 KHz so as to obtain the actual drivs frequency. For example, the value of 140 equals 14 XHz. The value of FUND PWM is the amount of delay time (dead space) between the two complementary drive signals DRIVEl and DRIVE2, as shown in Figure 3. This value is settable between 128 to 256.
This value i~ multiplied by .025 uS so as to determine the amount of dead space. For exampl~, 245 e~uals 6.125 uS. The delay incxeases efficiency and lowers th~
amount of heat dissipation Pro~ the drive transistors Q1 and Q2. The other constant value includes overload de~
lay, soft fault delay, so~t fault retries, hard fault retries, and the number of hours that the high voltage output has been on as well as the others listed in Table 5.
` ~ q ~ 3, ~
_30_ CASE 751 The personal computer communicates with the micro-controllex U4 by an RS/232 port which is used during en-~gineering development and service. The personal computer allows the power supply para~etexs, real time values, and 5setting to be easily viewed and/or changed. In par-ticular, all of the table parameters in the menus of Figures 7 through 9 are sent and received as 15-bit ..
binary words.
A ~ore detailed schematic circuit diagram of the 10high voltage module 14 of Figure 2 is shown in Figure 3a of U.S. Patent No. 4,74S,520, which is hereby incorporated by re~erence. There is shown in Figure 3a of the '520 patent a high vol~age transformer 72 and a high potential rectifier and multiplier 110. ~urther, 15there is shown the resistor 124 connected betwee~ grou~d and ihe terminal 120 for providing a voltage signal which corresponds to the multiplier 110 output current. This corresponds to the current feedback signal on the line 70 of Figure 2. Further, there is provided in the '520 20patent the series of resistors 130, 132 and 124 coupled between the terminals 114 a~d 120 so as to provide a voltage signal which corresponds to the output voltage.
This corresponds to the voltage feedback signal on the line 76 of Figure 2.
, ,.
In operation, the normal high voltage turn-on -- process is achieved through the micro-controller U4 by initially energizing the two complementary switching FET
Q1 and Q2 connected to the ends of the primary winding P
5 of the high voltage ~ransformer 48. Then, the FET Q4 connected between the pulse width modulator integrator ~ ~ r circult U17 and the switching regulator 62 will be energized so as to control the D.C. voltage level at the center tap 54 of the primary winding P. This D.C.
voltage level is alternately switched through the two halves of the primary winding P by the two FETS Q1 and Q2 under the control of the micro-controller V4. As a result, there is induced voltage variations in the secondary winding S of the high voltage transformer 48.
Finally, the high voltage output will be ramped up to the final desired value by increasing the center tap voltage.
The center tap voltage is controlled by modulation of the width of the pulses at the gate of the FET Q4.
As the high voltage i5 ramped up, the rate of change of the "pack return" (current feedback) is compared against the stored normal turn-on values o~ Table 2 in Figure 7. This current feedback is also compared with the present setting o~ the current limit value in Table 1 of Figure 7. Thus, the high voltage turn-on curve is dependent upon the value of the current feedback as well ~- 'as being ti~e dependent.
The micro-co~troller U4 will fetch the fundamental ,. . . .
drive ~requency and the PWM values from the stored constants in Table 5 o~ Figure 9 for the first and second drive signals DRIVE1 and DRIVE2. Then, the micro-controller U4 will activate the signal CT-DRIVE at the fundam6ntal frequency and minimum PWM value. The micro-controller will increase the PWM value until the desiredhigh voltage output is reached. During this turn-on process, the micro-controller will monitor all of the safety circuits (i.e., the current feedback signal I-FB
and corona sense signal CORONA). The high voltage will be ramped up in accordance with the stored turn-on values. If the current ~eedback or the corona sense values exceed the respective stored values, the power supply will overload and disconnect the hiyh voltage output, and the FAULT lamp 90c will be turned on. On the other hand, once the operatlng value of the current KV SET (Table l) has been reached, this will be the ready-~tate condition.
_33_ CASE 751 It should be understood that an overload condition will occur when any of the safety circuits determine that -- the preset value has been exceeded. I~ it i6 determined that the overload is a ~soft fault" where the high voitage output is being reduced in response to the SLOPE
setting and has encountered the 20 KV minimum voltage or ~ I ~ t the corona sense limit has been exceeded, the power supply will attempt to recover from the "soft fault" a predetermined number of times as stored in the constants table. However, if the overload is a "hard fault" where the current limit setting has been exceeded or the di/dt value has been exceeded, no recovery will be attempted.
After the steady-state value of the high voltage has been reached, this period is referred to as "HIG~ VOLTAGE
lS ON." The micro-controller will perform the algorithm stored in the non-volatile memory so as to optimize the efficiency of the high voltage moduleO In particular, the micro-controller will sweep the fundamental frequency of the switching regulator so as to obtain the lowest value of the center tap voltage V-CT. The range of the allowable frequency and the increment of change are determined by the constants in Table 5. The micro-controller w~ll monitor the value HV-ON ~OURS and will attempt to optimize the value of the voltage V-CT every ~ 3 ~3 ~ 8 .~5 hours. During the normal "HV ON" interval, the current feedback will be changed routinely in response to the passage of the target or article to be coated and the triggering of the coating makerial. The power supply will attempt to maintain the desired high voltage output at the out,put terminal 24 as the current feedback chang~s by ad~usting the PWM value.
The high voltage power supply of the present invention has the following advantages over the pr:ior art:
(1) It uses a controller operated under a stored program to perform all control, safety and operating diagnostics;
(2) It provides a large amount of versatility and ~15 adaptability to changes in design parameters or different applications by changes in software only;
(3) It provides a non-volatile memory for storage of current setting parameters, turn on table values, and constants for use by the controller; and (4) It provides a personal computer connectible to the controller so as to easily alter the operation of the ~ power supply or retrieve diagnostic in~ormation.
From the foregoing detailed description, it can thus 1~ t 1- .
be seen that the present invention provides an impro~ed high voltage power supply for use in electxostatically~
aided coating material application equipment :Eor dispensing electrostatically charged particles of coating material which includes a control module having a controller operated under a stored program to perform control functions, safety and operating diagnostics. A
non-volatile memory is provided for storing current para-meter settings, turn-on table values, and a constants ~able. A personal computer is connectible to the controller by a communication li~k to permit changing of the values stored in the non-volatile memory so as to facilitate engineering development and servi~e.
While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for 3,~
-36~ CASE 751 elements thereof without departing from the true scope of the invention. In addition, many modifications may be ~~ made to adapt a particular situation or material to the teachings of the invention without departing from the central scope thereof. Therefore, it .is intended that this invention not be limited to the particular embodi-ment disc~o~edfas the best mode contemplated ~or carrying out the. invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (20)
1. A high voltage power supply for use in electrostatically-aided coating material application equipment for dispensing electrostatically charged particles of coating material, comprising in combination:
an electrostatic potential utilization device;
a high voltage module including a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output;
means for coupling said high voltage output to said utilization device;
a low voltage D.C. power source;
a control module including a switching type regulator responsive to said D.C. power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver circuits for switching the regulated operating voltage across the primary winding;
said control module including controller means for generating first and second drive signal for said switching drive circuits;
non-volatile memory means for storing current parameter settings, normal turn-on table values, fault turn-on table values, and a constants table; and said controller means being adapted to perform safety and operating diagnostics through a stored program based upon the settings and values obtained from said non-volatile memory means.
an electrostatic potential utilization device;
a high voltage module including a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output;
means for coupling said high voltage output to said utilization device;
a low voltage D.C. power source;
a control module including a switching type regulator responsive to said D.C. power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver circuits for switching the regulated operating voltage across the primary winding;
said control module including controller means for generating first and second drive signal for said switching drive circuits;
non-volatile memory means for storing current parameter settings, normal turn-on table values, fault turn-on table values, and a constants table; and said controller means being adapted to perform safety and operating diagnostics through a stored program based upon the settings and values obtained from said non-volatile memory means.
2. A high voltage power supply as claimed in Claim 1, wherein said utilization device comprises a coating atomizer.
3. A high voltage power supply as claimed in Claim 2, wherein said coating material is a liquid paint.
4. A high voltage power supply as claimed in Claim 1, further comprising a programmable pulse width generator responsive to control signals from said con-troller means for controlling the width of drive pulses applied to said switching regulator so as to vary the D.C. voltage level of the regulated voltage at the center tap of the primary winding.
5. A high voltage power supply as claimed in Claim 4, wherein said switching regulator includes a voltage divider for providing a regulator feedback voltage indicative of the voltage at the center tap to said controller means.
6. A high voltage power supply as claimed in Claim 5, wherein said high voltage module includes voltage sensing means for generating a voltage feedback signal indicative of the actual high voltage output to said controller means.
7. A high voltage power supply as claimed in Claim 6, wherein said high voltage module further includes current sensing means for generating a current feedback signal indicative of the actual output current to said controller means.
8. A high voltage power supply as claimed in Claim 7, further comprising a programmable bandpass filter responsive to said current feedback signal to produce a corona sense signal indicative of an incipient spark to said controller means.
9. A high voltage power supply as claimed in Claim 8, wherein said first and second drive signals are complementary having a programmable dead space time therebetween, the amount of said dead space time being dependent upon said current feedback signal.
10. A high voltage power supply as claimed in Claim 1, further comprising display means responsive to control signals from said controller means for displaying visually the actual values of the high voltage output and the output current.
11. A high voltage power supply as claimed in Claim 1, further comprising a personal computer connectible to said controller means over a communication link to permit changing dynamically of the values stored in said non-volatile memory means while in operation so as to facilitate engineering development and service.
12. A high voltage power supply as claimed in Claim 1, wherein said current parameter settings include a desired high voltage output, a current limit, a slope setting, and a corona sense.
13. A high voltage power supply as claimed in Claim 1, wherein said normal turn-on table values include turn on times, corona values, and timed rate of change of the output current.
14. A high voltage power supply as claimed in Claim 1, wherein said fault turn-on table values include turn on times, corona values, and timed rate of change of the output current.
15. A high voltage power supply as claimed in Claim 1, wherein said constants table include a funda-mental drive frequency and a fundamental PWM value.
16. A high voltage power supply for use in electrostatically-aided coating material application equipment for dispensing electrostatically charged particles of coating material, comprising in combination:
an electrostatic potential utilization device;
a high voltage module including a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output;
means for coupling said high voltage output to said utilization device;
a low voltage D.C. power source;
a control module including a switching type regulator responsive to said D.C. power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver circuits for switching the regulated operating voltage across the primary winding;
said control module including controller means for generating first and second drive signals for said switching drive circuits;
non-volatile memory means for storing current parameter settings, normal turn-on table values, fault turn-on table values, and a constants table;
said controller means being adapted to perform safety and operating diagnostics through a stored program based upon the settings and values obtained from said non-volatile memory means;
said high voltage module including voltage sensing means for generating a voltage feedback signal indicative of the actual high voltage output to said controller means;
said high voltage module further including current sensing means for generating a current feedback signal indicative of the actual output current to said controller means; and display means responsive to control signals from said controller means for displaying visually the actual values of the high voltage output and the output current.
an electrostatic potential utilization device;
a high voltage module including a high voltage transformer having a primary winding and a secondary winding and a high potential rectifier and multiplier for generating a high voltage output;
means for coupling said high voltage output to said utilization device;
a low voltage D.C. power source;
a control module including a switching type regulator responsive to said D.C. power source for generating a regulated operating voltage to a center tap of the primary winding and first and second switching driver circuits for switching the regulated operating voltage across the primary winding;
said control module including controller means for generating first and second drive signals for said switching drive circuits;
non-volatile memory means for storing current parameter settings, normal turn-on table values, fault turn-on table values, and a constants table;
said controller means being adapted to perform safety and operating diagnostics through a stored program based upon the settings and values obtained from said non-volatile memory means;
said high voltage module including voltage sensing means for generating a voltage feedback signal indicative of the actual high voltage output to said controller means;
said high voltage module further including current sensing means for generating a current feedback signal indicative of the actual output current to said controller means; and display means responsive to control signals from said controller means for displaying visually the actual values of the high voltage output and the output current.
17. A high voltage power supply as claimed in Claim 16, further comprising a programmable pulse width generator responsive to control signals from said con-troller means for controlling the width of drive pulses applied to said switching regulator so as to vary the D.C. voltage level of the regulated voltage at the center tap of the primary winding.
18. A high voltage power supply as claimed in Claim 17, wherein said switching regulator includes a voltage divider for providing a regulator feedback voltage indicative of the voltage at the center tap to said controller means.
19. A high voltage power supply as claimed in Claim 16, further comprising a programmable bandpass filter responsive to said current feedback signal to produce a corona sense signal indicative of an incipient spark to said controller means.
20. A high voltage power supply as claimed in Claim 19, wherein said first and second drive signals are complementary having a programmable dead space time therebetween, the amount of said dead space time being settable in the constants table.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US5246793A | 1993-04-26 | 1993-04-26 | |
| US08/052,467 | 1993-04-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2119958A1 true CA2119958A1 (en) | 1994-10-27 |
Family
ID=21977792
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2119958 Abandoned CA2119958A1 (en) | 1993-04-26 | 1994-03-25 | Micro-controller based high voltage power supply |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH06320066A (en) |
| CA (1) | CA2119958A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5390259B2 (en) * | 2009-05-22 | 2014-01-15 | 旭サナック株式会社 | Electrostatic coating apparatus and coating method |
| JP5508622B2 (en) | 2009-10-02 | 2014-06-04 | トヨタ自動車株式会社 | High voltage generator disconnection detection method |
| CN105413902B (en) * | 2015-12-09 | 2018-02-27 | 华南理工大学 | A kind of electrostatic powder coating controller and control method |
| JP6890978B2 (en) * | 2017-01-11 | 2021-06-18 | 日本電波株式会社 | High voltage power supply for electrostatic coating equipment |
| JP6856833B2 (en) * | 2017-01-25 | 2021-04-14 | 日本電波株式会社 | High voltage controller |
| JP6945433B2 (en) * | 2017-12-13 | 2021-10-06 | 日本電波株式会社 | Self-diagnosis method for electrostatic coating system |
-
1994
- 1994-03-25 CA CA 2119958 patent/CA2119958A1/en not_active Abandoned
- 1994-04-26 JP JP8869494A patent/JPH06320066A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06320066A (en) | 1994-11-22 |
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