Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs MODEL POWER I-CONT I-PEAK FEATURES 4122D +22 to +90 VDC 10 20 4212D +22 to +125 VDC 6 12 • Component socket configures amp completely • Flexibility! Internal 40-pin socket configures amp with no soldering • Separate current limits: Continuous, peak, and peak-time • No integrator windup when disabled • Fault protections: Short-circuits from output to output, DESCRIPTION output to gnd Over/under voltage Models 4122D and 4212D are third-generation amplifiers for dc Over temperature brush motors from Copley Controls Corp. Built using surface-mount technology, these amplifiers offer plug and play operation in a very Self-reset or latch-off modes small package. Both models take digital, one or two wire PWM • 3kHz Current Loop Bandwidth signals as command inputs, and convert them to internal ±10V to • Wide load inductance range: 0.2-40 operate motors in torque or velocity mode. mH. Two-wire PWM data format interfaces with microcontrollers such as • Surface mount technology construc- the National LM-629, or control cards that output a 0% to 100% PWM signal for magnitude, and a DC signal for direction. Positive or tion, lower part count. negative logic levels are jumper-selectable. One wire format uses a 50% duty cycle PWM command for ‘0’ and APPLICATIONS 0% or 100% duty cycles for positive and negative full-scale. A differential analog input takes brush tachometer signals for • X-Y stages velocity-loop operation. • Robotics Model 4122D operates from +22 to +90VDC unregulated power supplies, and outputs 10A continuous, 20A peak. • Automated assembly machinery Model 4212D operates from +22 to +125VDC power supplies, and • Magnetic bearings outputs 6A continuous, and 12A peak. The active logic-level of the amplifier Enable input is jumper select- THE OEM ADVANTAGE able to GND or +5V to interface with different control cards. The /Pos and /Neg enable inputs remain ground active for fail-safe • Conservative design for high MTBF operation. • No soldering required to change A mosfet H-bridge output stage delivers power in four-quadrants for header parts. bi-directional acceleration and deceleration of motors. An internal solderless socket holds 17 components that configure • Custom configurations available the various gain and current limit settings to customize the amplifiers (contact factory) for a wide range of loads and applications. No-pots, custom headers Header components permit compensation over a wide range of load inductances to maximize bandwidth with different motors. Individual peak and continuous current limits allow high acceleration without sacrificing protection against continuous overloads. Peak current time limit is settable to match amplifier to motor thermal or commutation limits. All models are protected against output short circuits ( output to output and output to ground ) and heatplate overtemperature. With the /Reset input open, output shorts or heatplate overtemperature will latch off the amplifier until power is cycled off & on, or until the /Reset input is grounded. For self-reset from such conditions, wire /Reset to ground and the amplifier will reset every 200ms. A bicolor led speeds diagnostics during set-up, or for fault isolation after the unit is in service. 49 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs FUNCTIONAL DIAGRAM * JP1: PINS 2-3 FOR /ENABLE AT J2-11 GND PINS 1-2 FOR /INHIBIT AT J2-11 10 LM-629 ENABLE PWM BOARD 3 2 1 * INTEGRATOR RESET SWITCHES 11 *JP1 RH5 TURN ON WHEN AMP IS DISABLED PWM 19 PWM PWM MAG POS ENABLE 6 TO LED 12 100 K +/-10v INTEGRATOR GREEN = NORMAL STATUS 18 DIR ANALOG NEG ENABLE RED = FAULT & PWM SIGN 16 13 CONVERSION CONTROL CH9 (OPEN) NOTE: +5V LOGIC * +FAULT OUTPUT 14 DEFAULT VALUE OF CH11 IS 0 OHMS FOR TORQUE MODE OPERATION RESET 15 FOR VELOCITY MODE ( BRUSH TACH ) TACH(-) / GND CH11 RH10 * CH17 MOMENTARY SWITCH CLOSURE RESETS FAULT SEE APPLICATIONS SECTION RH15 2 WIRE RESET TO GROUND FOR SELF-RESET - 60.4 K +/-10V TACH LEAD MAX RH6 CH8 J2 SIGNAL CONNECTOR CURRENT LIMIT Rext CH16 SECTION + 100PF 4 - - 47K TACH VALUE DEPENDS ON MODEL - - SEE "ARMATURE INDUCTANCE" TABLE + + RH7 100 K 5 TACH AMP RH12 182K + + PEAK Gv = 1 Rin = 47K SERVO CURRENT CURRENT J1 MOTOR & POWER CONNECTOR 7 ERROR GND PREAMP 47K AMP RH13 4.7MEG CONT CURRENT MOTOR +15V CH14 0.47U PWM PEAK STAGE CW RH1 + - TIME OUTPUT MOSFET BALANCE CURRENT "H" MOTOR + 10 MEG Voltage gain = 1 50K SENSE BRIDGE 1 -15V MOTOR - 2 +/-6V for VOLTAGE GND 1K +/-Ipeak CURRENT GAIN 3 9 REF GND 4.8 kHz FILTER Gv = +HV 4 33NF 10 +HV +/-6V at 5 1K CURRENT +/-Ipeak 8 MONITOR 4.8 kHz FILTER 33NF 1K +HV 10k CASE MAY BE GROUNDED +5 +15 +15V 1 AUXILIARY DC / DC FOR SHIELDING +15 CONVERTER DC OUTPUTS 10k -15 -15V -15 3 CASE GROUND NOT CONNECTED TO CIRCUIT GROUND POWER GROUND AND SIGNAL GROUNDS ARE COMMON typical connections VELOCITY MODE ENCODER TORQUE MODE ENCODER + PWM + PWM 6 1 6 1 J1 J2 MOTOR J1 J2 MOTOR DIR DIR 16 2 16 2 + 4 J2 TACH 5 10 GND GND 10 ENABLE 11 ENABLE 11 3 3 12 12 J1 J1 POS ENABLE 4 GND POS ENABLE 4 GND + + NEG ENABLE 13 5 NEG ENABLE 13 5 +HV +HV Note: JP1 on pins 2-3 ( default ) Note: JP1 on pins 2-3 ( default ) Notes 1. All amplifier grounds are common (J1-3, J1-4, J2-2, J2-7, and J2-10 ) Amplifier grounds are isolated from case & heatplate.. 2. Jumper JP1 default position is on pins 2-3 for ground active /Enable input ( J2-11 ) For /Inhibit function at J2-11 ( +5V enables ), move JP1 to pins 1-2 3. For best noise immunity, use twisted shielded pair cable for tachometer inputs. Twist motor and power cables and shield to reduce radiated electrical noise from pwm outputs. 50 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs TECHNICAL SPECIFICATIONS Test conditions: 25°C ambient, Load = 200μH. in series with 1 Ω., +HV = maximum normal value MODEL 4122D 4212D OUTPUT POWER Peak power ±20A @ ±80V ±12A @ ±120V Peak time 1 sec unipolar from 0A, 2 secs. after polarity reversal Continuous power ±10A @ ±80V ±6A @ ±120V OUTPUT VOLTAGE ±Vout = ±HV*(0.97) - (Ro)*(Io) Ro = 0.2 Ro = 0.1 LOAD INDUCTANCE Selectable with components on header socket: 200 μH to 40mH BANDWIDTH Reference PWM inputs 1.5kHz Output PWM stage: 3kHz with 200μH load at maximum supply voltage, varies with load inductance and RH15, CH16 & CH17 values PWM OUTPUT BRIDGE SWITCHING FREQUENCY 25kHz REFERENCE LOGIC INPUTS Digital, pulse-width modulated ( PWM ). One or two-wire format, positive or negative logic. Logic threshold 2.5VDC. Input voltage range 0 to +12V. GAINS Input PWM to analog conversion 100% duty cycle produces ±10V to preamplifier stage. PWM transconductance stage Ipeak / 6V ( I peak = peak rated output current; 6V measured at Current Ref J2-9 ) CONTROL LOGIC INPUTS Input voltage range 0 to +24V Logic threshold voltage ( LO to HI transition ) 2.5V ( Schmitt trigger inputs with hysteresis ) /Enable ( Internal jumper JP1 reverses logic ) LO enables amplifier, HI disables ( Default function with JP-1 on pins 2-3. For +5V enable and GND inhibit, move JP1 to pins 1-2 ) Time delay on Enable 0.9 ms after Enable true to amplifier ON, <1ms to disable /POS enable, /NEG enable Gnd enables positive or negative output currents. +5V or open inhibits (<1ms delay) ( Setting of JP-1 has no effect on ground-active level of /POS and /NEG enable inputs ) /Reset LO resets latching fault condition, ground for self-reset every 200 ms. Input resistance 10K pull-up to +5V, R-C filters to internal logic POTENTIOMETER Balance Use to set output current or rpm to zero. RH1 = 10 MΩ for Balance function, RH1 = 100kΩ for Test function LOGIC OUTPUT +Fault ( /Normal ) HI = Overtemp OR output short OR power NOT-OK, OR NOT-Enabled; LO = Operating normally AND enabled HI output voltage +5V ( 3.3kΩ pullup resistor to +5V ) +50V maximum LO output voltage <0.5V typical, 1.25V @ 250mA max, Ro = 5Ω ( mosfet on resistance ) INDICATOR (LED) Normal Green: ON = Amplifier Enabled AND Normal ( power OK, no output shorts, no overtemp ) Red = Fault ( NOT Normal, amplifier NOT enabled, or fault condition ) ANALOG MONITOR OUTPUTS Current Ref ( current demand signal to pwm stage ) ±6V @ demands ±Ipeak Current Monitor ( motor or load current ) ±6V @ ±Ipeak (1kΩ, 33nF R-C filter) DC POWER OUTPUTS ±15VDC each output in series with 10kΩ PROTECTIVE FEATURES ( Note 1 ) Output short circuit (output to output, output to ground) Latches unit OFF Overtemperature Latches unit OFF at 70°C on heatplate Undervoltage shutdown @ <20V <20V Overvoltage shutdown @ >92VDC >129VDC POWER REQUIREMENTS DC power (+HV) Transformer isolated from power mains +22 to +90VDC +22 to +125VDC Watts minimum 2.5W 2.7W Watts @ Icont 25W 41W THERMAL REQUIREMENTS Storage temperature range: -30 to +85°C; operating temperature range: 0 to 70°C baseplate temperature Notes: 1. Heatsink optional ( add “H” to model number) 2. Fan = forced air over unit @ 400 linear feet/minute MECHANICAL Amplifier case size 4.3 x 3.0 x 1.18 in. (109 x 76.2 x 30 mm.) Heatsink Adds 1.50 in. ( 38.1 mm ) to amplifier 1.0 in. dimension. Same length as amp. Weight 0.43 lb (0.2 kg.) for amplifier alone; heatsink adds 0.78 lb. (0.35 kg) CONNECTORS 2 2 J1 (Power & motor): 5 position compression-connector; Phoenix MKDS 3; maximum wire gauge AWG 12 ( 4 mm solid or 2.5 mm stranded ) wire. J2 (Signal): 16-position 0.1” centers housing ( Molex: 22-01-3167 ) with AWG 30-22 crimp contacts ( Molex 08-50-0114 , 16 required ) NOTES 1. Latching faults disable amplifier until power is cycled off-on, or /Reset input is grounded. Non-latching faults re-enable amplifier when fault condition is removed. Overtemperature and short-circuits are latching faults, under or overvoltage faults are non-latching. If /Reset input is grounded, amplifier will auto- reset from latching faults every 200ms. 51 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs CONNECTORS AND PINOUTS J1: MOTOR & POWER CONNECTIONS Pin Signal Remarks 1 Motor (+) Amplifier output to motor (+) winding 2 Motor (-) Amplifier output to motor (-) winding 3 GND Power supply return. Connect to system ground at this pin. 4 GND Power supply return. Connect to system ground at this pin. 5 +HV +HV DC power supply input J2: AMPLIFIER BOARD CONNECTIONS Pin Signal Remarks 1 +15V +15V in series with 10kΩ 2 Gnd Signal ground 3 -15V -15V in series with 10kΩ 4 Tach (+) Tachometer feedback input. ±20V maximum between J2-4 and J2-5 without external scaling. 5 Tach (-) Tachometer feedback input. ±20V maximum between J2-4 and J2-5 without external scaling. 6 PWM input Digital reference input. 0% to 100% duty cycle controls output current magnitude. ( Note 1 ) 7 Gnd Signal ground 8 Curr Mon Output current monitor: ±6V output at ±peak output current 9 Curr Ref Current demand signal to output PWM stage: ±6V demands ±peak current 10 Gnd Signal ground 11 /Enable Amplifier enable input: enables or inhibits PWM switching at outputs Default: Gnd enables amplifier, open or +5V inhibits ( JP1 @ 2-3 ) For controllers that output +5V to enable amplifier, move internal jumper JP1 to pins 1-2 ( Gnd will inhibit, +5V or open will enable ) 12 /Pos Enab Gnd to enable output current in one polarity, open or +5V to inhibit Typically used with grounded, normally closed limit switches. 13 /Neg Enab Gnd to enable output current in opposite polarity, open or +5V to inhibit. Typically used with grounded, normally closed limit switches. 14 /Normal Current-sinking when amplifier enabled and operating normally. Goes to +5V when amplifier disabled or fault condition exists. 15 /Reset Ground to reset overtemp or output short circuit latching faults. For automatic reset of faults every 200mS, ground permanently. 16 DIR input Output current polarity ( direction ) input. Polarity switches from positive to negative with DC level of input. ( Note 1 ) BALANCE POTENTIOMETER Default position: centered. Functions to bring output current ( in torque mode ) or output velocity ( in tachometer mode ) to zero with control system outputs at zero. Normal range is ±1% of full scale with 10Meg resistor in header location RH1. To use the pot as a wide range set-point adjustment, install a 150kΩ resistor at RH1. Now, full CW or CCW will have the effect of a 100% duty-cycle signal at the PWM inputs. STATUS LED Color +HV /Enable Short Overtemp Green Normal Active None Normal Red Too low or too high X X X X Inhibited X X X X Output short X X X X Too hot Note 1, 5 2, 5 3, 5 4, 5 Notes: 1. Input function changes with input type. See Applications section for details. 2. +HV normal >20V and <92V for model 4122D, >20V and <129V for model 4212D 3. /Enable is ground-active for JP1 on pins 2-3 ( default ). To reverse function, switch JP1 to pins 1-2. 4. Shorts detected by overcurrent circuit are between outputs, or from outputs to ground. 5. Overtemperature faults occur when heatplate temperature is >70°C 6. +HV and /Enable cause momentary amplifier shutdown, operation is restored when +HV is within normal limits and /Enable input is active. Output shorts, and overtemperature faults latch-off amplifier. Thus amplifier will remain off until power is cycled on/off, or /Reset input is grounded momentarily. If /Reset input is wired to ground, output short and overtemperature faults will self-reset every 200ms. 52 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs COMPONENT HEADER HEADER SOCKET NO PARTS INSTALLED IN THESE LOCATIONS AMPLIFIER BOARD CH17 LOAD INDUCTANCE COMPENSATION CH16 (SEE CHART FOR VALUES) PWM BOARD RH15 CH14 PWM MODE JUMPERS 0.47UF PEAK TIME LIMIT RH13 CONTINUOUS CURRENT LIMIT 4.7 MEG JP2 D C B A 182K RH12 PEAK CURRENT LIMIT POSITIVE LOGIC CH11 (O OHM) TWO-WIRE PREAMP DC GAIN & INTEGRATOR NEGATIVE LOGIC RH10 60.4K DEFAULT POLARITY CH9 PREAMP HI-FREQUENCY ROLL-OFF (SEL) ONE-WIRE OPPOSITE POLARITY (SEL) CH8 TACH INPUT LEAD CAPACITOR RH7 TACH INPUT SCALING 100K JP1 RH6 TACH INPUT LEAD RESISTOR (SEL) 3 2 1 D C B A RH5 PWM INPUT SCALING 100K J1 JP2 J2 NO FUNCTION, DO NOT USE 5 1 16 1 NO FUNCTION, DO NOT USE NO FUNCTION, DO NOT USE COMPONENTS LABELLED "SEL" RH1 BALANCE RANGE ARE NOT INSTALLED AT FACTORY USER SHOULD SELECT VALUES AS REQUIRED ARMATURE INDUCTANCE Model 4122D 4212D Load (mH) RH 15 CH17 CH16 RH15 CH17 CH16 0.2 to 0.5 80.6k 2.2 nF 390 pF 69.8 k 2.2 nF 390 pF 0.6 to 1.7 200k 680 pF 220 pF 100 k 1 nF 330 pF 1.8 to 4.8 402k 680 pF 180 pF 301 k 470 pF 100 pF 5 to 14 806k 680 pF 150 pF 698 k 330 pF 82 pF 15 to 45 1.5M 470 pF 100 pF 1.21M 220 pF 82 pF Note: Values in bold & italics are factory installed standard. Values shown are for 90V (4122D ) and 125V (4212D). At lower supply voltages RH15 may be increased and CH17 decreased. PEAK CURRENT LIMIT (AMP) CONTINUOUS CURRENT LIMIT (AMP) 4122D 4212D RH12 (Ω) 4122D 4212D RH13 (Ω) 20 12 182k 10 6 4.7Meg 16.7 10 56k 7.4 4.4 7.15Meg 13.3 8 30k 5.7 3.4 10Meg 10 6 18k 6.7 4 9.1k 3.3 2 3.9k Notes on Current Limits: 1. Values in bold & italics are factory installed standard. 2. Peak times double after polarity reversal. PEAK CURRENT TIME-LIMIT (SEC) 3. Peak current limit should be set greater than continuous current limit. Tpeak CH14 (μF) If Ipeak < Icont then peak overrides continuous limit and Icont = 1 0.47 Ipeak. 0.8 0.33 Minimum setting for peak current is 0% of peak rating. 4. Continuous current sense is for average current. Symmetrical 0.5 0.22 waveforms with zero average value may cause overtemperature 0.3 0.15 2 shutdown of amplifier or motor damage due to high I R losses. 0.2 0.10 5. Times shown are for 100% step from 0A with default value of 0.1 .047 RH13 ( 4.7 Meg ). When changing RH13, peak times will change. Set RH13 for continuous current limit first, then pick CH14 based on waveforms at Curr Ref ( J2-9 ). 53 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs is used most frequently in systems that have controllers tak- APPLICATION INFORMATION ing feedback from an encoder on the motor shaft. The com- puter calculates both position and velocity from the encoder IMPORTANT! ALWAYS REMOVE POWER WHEN CHANGING signal, processes them in a digital filter, and outputs a signal HEADER PARTS!! to the motor causing it to accelerate or decelerate. PWM REFERENCE INPUTS velocity mode PWM ( pulse-width modulated ) inputs are digital signals that carry the information for magnitude and sign of the As a feedback amplifier, a signal is generated by an analog output current, or the motor velocity. Magnitude informa- brush tachometer mounted on the motor. This is a generator tion tells the amplifier to output from zero to 100% of its that produces an analog signal that has a polarity and ampli- rated current. Sign information defines the polarity ( tude proportional to the motor speed. The servo preamplifier positive or negative ) of the output current, or the direction subtracts the tach signal from the reference signal, and am- of the motor rotation. plifies the difference between them, changing the motor cur- rent ( torque ) so that the motor velocity is proportional to the reference signal. Two-wire PWM data Also called 100% modulation, this type used two lines. THE PARTS OF THE AMPLIFIER The PWM input has a duty cycle that ranges from 0% to 100% and controls the magnitude of the output current PWM INPUT CIRCUIT ( or the percent of maximum velocity ). The DIR input controls the sign of the output current ( or the direction of The PWM card has circuits that convert the digital PWM ref- motor rotation ). erence signal(s) into an internal ±10V reference signal that Positive or negative logic can be used. In positive logic, drives the servo preamplifier. Header component RH5 con- the zero level is OFF, and the one-level controls magni- trols the scale factor and has a default value of 100kΩ. With tude. In negative logic, +5V is the zero-level, with ground two-wire inputs, a 100% duty cycle signal is converted to a transitions controlling magnitude. To reverse the function of the DIR input, simply reverse ±10V analog signal with the polarity following the DC level at the connections between the motor to the Mot(+) and the DIR input. With the default values in the header, this is Mot(-) terminals. If a tachometer is used, reverse both then scaled to ±6V after the current limit stage, which then motor and tachometer wires. drives the output PWM stage to its peak rated current. one-wire PWM data THE SERVO PREAMPLIFIER Also called 50% modulation, this format uses only one line This section processes the reference signal and any feed- which connects to the DIR input. The PWM input is left back signals, and generates an internal current reference open. The PWM signal has a duty cycle of 50% that signal that controls the PWM stage to produce output cur- represents zero output from the amplifier. A 0% duty cycle rents. In torque mode the stage simply scales the ±10V in- then represents full output in one polarity, and a 100% duty cycle represents full output in the opposite polarity. ternal reference input to ±6V for the output PWM stage. And, To reverse the function of the DIR input, simply reverse it is here that the reference signal and tachometer signals the connections between the motor to the Mot(+) and are compared, and the difference signal produced and am- Mot(-) terminals. If a tachometer is used, reverse both plified. motor and tachometer wires. Three components on the header control the behavior of the servo preamp. The chart below lists the default torque-mode PWM mode jumpers and starting-point values for velocity mode operation: There are four jumpers at location JP2 on the PWM card. Part Torque Velocity The chart below shows their positions and functions as CH9 out 220pF they relate to the different input types. The two-wire RH10 60.4k 680k positive logic connection is the default. CH11 short 4.7nF D C B A DEFAULT CH9 controls the high-frequency roll-off. POSITIVE LOGIC RH10 controls the loop gain, and thus the step-response TWO-WIRE NEGATIVE LOGIC of the amplifier. CH11 ( along with RH7 ) forms the integrator that gives the DEFAULT POLARITY ONE-WIRE stiffness at a standstill, or speed regulation while run- OPPOSITE POLARITY ning. CURRENT LIMITING These amplifiers operate as either open-loop current sources, or feedback devices using analog tachometers. Current in a This stage takes the output of the servo preamplifier, and motor winding produces torque, and a tachometer voltage processes it before sending it to the PWM stage. The ampli- shows motor velocity. From this we get torque mode, and tude of the signal is first clamped to produce peak current velocity mode. limiting. This signal then goes to the continuous current-limit circuit where these functions are produced. Finally, the cur- Torque mode rent-limited signal is outputted to the PWM stage as the cur- rent-reference signal. This signal is quite useful in that the As open-loop current sources, the PWM signals at the refer- current limit action can be seen here and measured without ence inputs produce current in the load, typically a motor. It connecting a motor, thus protecting it from overload during initial setup. 54 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs OUTPUT PWM STAGE /ENABLE INPUT The voltage at the output of the current limit stage is called With internal jumper JP-1 on pins 2-3 ( default position ), the the current reference. This signal becomes the demand sig- /Enable input ( J2-11 ) must be grounded for the amplifier to nal that controls the PWM stage. Here the current demand is operate. For operation with cards that output +5V to enable the amplifier, move the jumper on JP-1 to pins 1-2. This will converted into a current in the motor. This current can be measured at the current monitor, which shows the response reverse the /Enable input active level so that grounding the of the motor to the current demand signal. By operating as a input will inhibit the amplifier, and +5V (or open) will enable. Note: There is a 0.9ms delay /between Enable TRUE and current source, the PWM stage is able to achieve faster re- sponse from the motor than if was acting only as a variable amplifier ON. voltage. /POS & /NEG ENABLE INPUTS current error amplifier compares the current reference The with the current monitor, and adjusts the output voltage such These inputs are always ground active, open circuit or +5V that the demanded current flows in the motor. The gain of will inhibit. In service these would be grounded through nor- this amplifier is controlled by RH15, CH16, and CH17, which mally-closed limit switches. When a motion axis enters the are used to compensate the amplifier for the motors’ induc- limit, torque will be inhibited to prevent further travel into the tance. limit, but torque will be available to back-out of the limit switch. Because torque is still available in one direction, the Normal INSTALLING THE AMPLIFIER led stays ON, and the Normal output signal remains true. Delay on /Pos and /Neg enables is <1ms. Select the header components for current limits first as this will protect the motor during later procedures. Using the Current Ref signal will allow you to view the effect of TORQUE MODE SETUP component changes on the current demand signal without loading the motor until the adjustments are complete. The 1) Select RH12, RH13, and CH14 for motor current-limits. effects of the current limits can best be seen by moving the 2) Select RH15, CH16, and CH17 for armature inductance. PWM jumper from B to A and inputting a TTL ( 0 / +5V ) 3) Ground the /Enable, /Pos Enable, and /Neg Enable in- level square wave of about 1/4 Hz at the DIR input with the puts to PWM input open-circuit. This way there will be enough J2-10. ( Assumes default setting of JP-1 to pins 2-3 ) time at peaks to observe the peak time ( which will twice 4) Connect amplifier to transformer-isolated DC power sup- the unipolar time after reversals ) and to see the continu- ply. ous current value after the peak time occurs. 5) Adjust value of RH10 if necessary to change transconductance. PEAK CURRENT LIMIT Amplifiers are shipped with 182kΩ installed in RH12. This VELOCITY MODE SETUP delivers the amplifiers peak rated current. For lower settings There are three basic steps to follow to set up the amplifier in use values from the table. velocity mode. CONTINUOUS CURRENT LIMIT 1) Tach Scaling: Select Rext, the external scaling resistor so that motor reaches desired top speed at 100% input Choose RH13 based on the motor manufacturers specifica- duty cycles. tion for your motor. Table values give basic settings. This 2) Loop Gain Adjust: Select RH10 and CH9 for best response setting keeps the motor within its thermal limits. Note that to step inputs. this limit measures average current and will not work on sym- 3) Integrator Frequency: Select CH11 for best steady-state metrical waveforms such as might occur during system os- speed regulation and stiffness at a standstill. cillation. Use an external thermal circuit breaker for protec- These adjustments are most easily made with a square-wave tion from such overcurrent faults. input of alternating polarity. A simple way of producing this PEAK-TIME LIMIT condition is to replace RH1 with a 1 Meg resistor, and rotate the balance pot fully CW. With the PWM jumpers in the de- Header component CH14 controls the length of time for which fault positions connect a +5V logic square wave to the DIR the amplifier will output peak current. When peak currents input ( J2-16 ) at a frequency of about 1/2 Hz. Connect an that are less than the amplifiers peak rated current, this time oscilloscope to the tach signal at J2-4. If the motor ‘runs- will increase, eventually becoming infinite as you reach the away’ when you power-up, reverse the tachometer connec- continuous current. After a polarity reversal, the peak time tions for stable operation. will be twice that of a unipolar current change. 1) Tach scaling: You must know the tachometer gradient, usu- GROUNDING & POWER SUPPLIES ally given in volts / krpm ( volts per thousand rpm ). Multiply this value, typically 3 or 7 v/krpm, by your top speed in krpm. Connect positive terminal of power supply to J1-5, negative If the result is greater than 10V, then you must add an exter- terminal to J1-4. For best results do not ground power sup- nal scaling resistor in series with one of the tachometer wires ply, but ground each amplifier with heavy wire from J1-3 to ( see functional diagram ). Find the value using this formula: equipment ‘star’ ground point. If power supply is >1m. from amplifiers, add local filter ca- Rext = ( MaxTachVolts X 5kΩ ) - pacitor near amplifiers (250μF minimum per amplifier). 50kΩ 55 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs VELOCITY MODE SETUP (cont’d) If your maximum voltage was 35V ( 7v/krpm X 5 krpm ), 3) Integrator Frequency Adjust ( Stiffness ): Remove the short- ing jumper at CH11 and replace with a 10nF capacitor. If the then Rext would be 125kΩ, or the next smaller value.. motor oscillates violently, change this to a 33nF and repeat 2) Loop Gain Adjust: Observe the leading edge of the tach the test. With the motor stable, observe the step response. signal. If it rises slowly and doesn’t overshoot, you can in- When the integrator functions well, you will observe some crease loop gain by increasing the value of RH10. Begin by overshooting at each edge of the square wave and the motor doubling it and re-test. Select the final value such that the will be ‘stiff’ at a standstill. The overshoot can be between 10- tach signal rises as fast as possible with the minimum over- 20%, and should settle cleanly to the steady-state value. shoot ( <5% ). To minimize noise in the step response, add Remove the square wave from the DIR input and twist the capacitance at CH9 until it affects the step response. Use motor shaft gently. With optimal adjustment it will oppose your the largest value that does not degrade the step response. twisting effort and will not ‘hunt’ when you release it. Smaller values of CH11 will increase overshoot to a step input and stiffness at a standstill. Select CH11 for the best stiffness and response to a square wave input. When you have finished these adjustments, replace the re- sistor at RH1 with the 10 Meg default value and adjust the motor speed to zero with no reference inputs. OUTLINE DIMENSIONS Dimensions in inches (mm.) 56 Models 4122D, 4212D DC Brush Servo Amplifiers with PWM Inputs OTHER DC BRUSH SERVO AMPLIFIERS 400 Family Six models operating from +24 to +225VDC, 5-15A continuous, 10-30A peak. Fully featured with adjustment potentiometers, voltage feedback with IR compensation. Model 403 For torque-mode only applications at low cost. +18 to +55VDC operation, 5A continuous, 10A peak Model 405 Same power output ratings as model 403, but provides tachometer function from digital encoders by frequency to voltage conversion. ORDERING GUIDE Model 4122D 20A peak, 10A continuous, +22 to +90VDC brush motor amplifier with PWM inputs Model 4212D 12A peak, 6A continuous, +22 to +125VDC brush motor amplifier with PWM inputs Options: 1. Add “PMF” to part number for “pins” version of amplifier with output edge filters on accessory mounting card. 2. Add “D” to part number for logic-level PWM inputs instead of ±10V analog inputs 3. Add “H” to part number for heatsink option. 4. Option digit sequence: amplifier with all options would be 4122DPMFDH or 4212DPMFDH. Telephone: (781) 828-8090 Corporate Offices: 20 Dan Road Fax: (781) 828-6547 57 E-mail: sales@copleycontrols.com Canton, MA 02021 www.copleycontrols.com