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one technology way, p.o. box 9106, norwood. ma 02062-9106, u.s.a. tel: 617/329-4700 fax: 617/326-8703 rev. 0 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a features current conditioning complete vector transformation on silicon three-phase 120 and orthogonal 90 signal transformation three-phase balance diagnosticChomopolar output dq manipulation real-time filtering applications ac induction motor control spindle drive control pump drive control compressor drive control and diagnostics harmonic measurement frequency analysis three-phase power measurement three-phase current conditioner AD2S105 functional block diagram general description the AD2S105 performs the vector rotation of three-phase 120 degree or two-phase 90 degree sine and cosine signals by trans- ferring these inputs into a new reference frame which is controlled by the digital input angle f . two transforms are in cluded in the AD2S105. the first is the clarke transform which computes the sine and cosine orthogonal components of a three-phase in- put. these signals represent real and imaginary components which then form the input to the park transform. the park transform relates the angle of the input signals to a reference frame controlled by the digital input port. the digital input port on the AD2S105 is a 12-bit/parallel natural binary port. if the input signals are represented by vds and vqs, respectively, where vds and vqs are the real and imaginary components, then the transformation can be described as follows: vds' = vds cos f C vqs sin f vqs' = vds sin f + vqs cos f where vds' and vqs' are the output of the park transform and sin f , and cos f are the trigonometric values internally cal- culated by the AD2S105 from the binary digital data f . the input section of the device can be configured to accept either three-phase inputs, two-phase inputs of a three-phase system, or two 90 degree input signals. the homopolar output indicates an imbalance of a three-phase input only at a user- specified level. the digital input section will accept a resolution of up to 12 bits. an input data strobe signal is required to synchronize the position data and load this information into the device counters. i s1 vds vqs sector multiplier sine and cosine multiplier input data strobe homopolar output homopolar reference +5v gnd 5v f position parallel data 12 bits 3 f -2 f cos ( q + 120 ) cos ( q + 240 ) sin q cos q cos q sin q cos q + f conv1 conv2 decode busy vds' vqs' sin q + f sector multiplier sine and cosine multiplier ia + ib + ic 3 i s2 i s3 a two-phase rotated output facilitates the implementation of multiple rotation blocks. the AD2S105 is fabricated on lc 2 mos and operates on 5 volt power supplies. product highlights current conditioning the AD2S105 transforms the analog stator current signals (i s1 , i s 2 , i s 3 ) using the digital angular signal (reference frame) into dc values which represent direct current (i ds ) and quadrature cur- rent (i qs ). this transformation of the ac signals into dc values simplifies the design of the analog-to-digital (a/d) conversion scheme. the a/d conversion scheme is simplified as the band- width sampling issues inherent in ac signal processing are avoided and in most drive designs, simultaneous sampling of the stator currents may not be necessary. hardware peripheral for standard microcontroller and dsp systems the AD2S105 off-loads the time consuming cartesian transfor- mations from digital processors and benchmarks show a signifi- cant speed improvement over single processor designs. AD2S105 transformation time = 2 m s. field oriented control of ac motors the AD2S105 accommodates all the necessary functions to pro- vide a hardware solution for current conditioning in variable speed control of ac synchronous and asynchronous motors. three-phase imbalance detection the AD2S105 can be used to sense imbalances in a three-phase system via the homopolar output.
AD2S105Cspecifications parameter min typ max units conditions signal inputs ph/ip1, 2, 3, 4 voltage level 2.8 3.3 v p-p dc to 50 khz ph/iph1, 2, 3 voltage level 4.25 v p-p dc to 50 khz input impedance ph/ip1, 2, 3 7.5 10 k w ph/iph1, 2, 3 13.5 18 k w ph/ip1, 4 1 m w mode 1 only (2 phase) sin & cos gain ph/ip1, 2, 3, 4 0.95 1 1.05 ph/iph1, 2, 3 0.56 vector performance 3-phase input-output radius error (any phase) 0.4 1 % dc to 600 hz angular error 1, 2 ph/ip 15 30 arc min dc to 600 hz ph/iph 30 arc min dc to 600 hz differential nonlinearity 1 lsb full power bandwidth 50 khz small signal bandwidth 200 khz analog signal outputs ph/op1, 4 ph/ip, ph/iph inputs output voltage 3 2.8 3.3 v p-p dc to 50 khz offset voltage 2 10 mv inputs = 0 v slew rate 2 v/ m s small signal step response 1 m s1 input to settle to 1 lsb (input to output) output impedance 15 w output drive current 3.0 4.0 ma outputs to agnd resistive load 2 k w capacitive load 50 pf strobe write 100 ns positive pulse max update rate 366 khz busy pulse width 1.7 2.5 m s conversion in process v oh 4v dci oh = 0.5 ma v ol 1v dci ol = 0.5 ma digital inputs db1Cdb12 v ih 3.5 v dc v il 1.5 v dc input current, i in 10 m a input capacitance, c in 10 pf conv mode (conv1, conv2) v ih 3.5 v dc v il 1.5 v dc input current 100 m a internal 50 k w input capacitance 10 pf pull-up resistor rev. 0 C2C (v dd = +5 v 5%; v ss = C5 v 5% agnd = dgnd = o v; t a = C40 c to +85 c, unless otherwise noted)
parameter min typ max units conditions homopolar output hpopCoutput v oh 4v dci oh = 0.5 ma v ol 1v dci ol = 0.5 ma hprefCreference 0.5 v dc homopolar output-internal i source = 25 m a and 20 k w to agnd power supply v dd 4.75 5 5.25 v dc v ss C5.25 C5 C4.75 v dc i dd 4 10 ma quiescent current i ss 4 10 ma quiescent current AD2S105 rev. 0 C3C notes 1 angular accuracy includes offset and gain errors, measured with a stationary digital input and maximum analog frequency inputs. 2 the angular error does not include the additional error caused by the phase delay as a function of input frequency. for example, if f input = 600 hz, the contribution to the error due to phase delay is: 650 ns f input 60 360 = 8.4 arc minutes. 3 output subject to input voltage and gain. specifications subject to change without notice. warning! esd sensitive device caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the AD2S105 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. recommended operating conditions power supply voltage (+v dd , Cv ss ) . . . . . . . . . 5 v dc 5% analog input voltage (ph/ip1, 2, 3, 4) . . . . . . 2 v rms 10% analog input voltage (ph/iph1, 2, 3) . . . . . . 3 v rms 10% ambient operating temperature range industrial (ap) . . . . . . . . . . . . . . . . . . . . . . . C40 c to +85 c absolute maximum ratings (t a = +25 c) v dd to agnd . . . . . . . . . . . . . . . . . . . . . . . C0.3 v to +7 v dc v ss to agnd . . . . . . . . . . . . . . . . . . . . . . . +0.3 v to C7 v dc agnd to dgnd . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 v dc analog input voltage to agnd . . . . . . . . . . . . . . . v ss to v dd digital input voltage to dgnd . . . . C0.3 v to v dd + 0.3 v dc digital output voltage to dgnd . . . . . . C0.3 v to v dd + v dc analog output voltage to agnd . . . . . . . . . . . . . . . . . . . . . . v ss C 0.3 v to v dd + 0.3 v dc analog output load condition (ph/op1, 4 sin q , cos q) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 k w power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 mw operating temperature industrial (ap) . . . . . . . . . . . . . . . . . . . . . . . C40 c to +85 c storage temperature . . . . . . . . . . . . . . . . . C65 c to +150 c lead temperature (soldering, 10 sec) . . . . . . . . . . . . . +300 c caution 1. absolute maximum ratings are those values beyond which damage to the device will occur. 2. correct polarity voltages must be maintained on the +v dd and Cv ss pins ordering guide model temperature range accuracy option* AD2S105ap C40 c to +85 c 30 arc min p-44a *p = plastic leaded chip carrier.
AD2S105 rev. 0 C4C pin designations 1, 2, 3 pin mnemonic description 3 strobe begin conversion 4v dd positive power supply 5v ss negative power supply 6 ph/op4 sin ( q + f) 7 ph/op1 cos ( q + f) 10 agnd analog ground 11 ph/ip4 sin q input 12 ph/iph3 high level cos ( q + 240 ) input 13 ph/ip3 cos ( q + 240 ) input 14 ph/iph2 high level cos ( q + 120 ) input 15 ph/ip2 cos ( q + 120 ) input 16 ph/iph1 high level cos q input 17 ph/ip1 cos (q) input 19 v ss negative power supply 20 hpref homopolar reference 21 hpop homopolar output 22 hpfilt homopolar filter 23 conv1 select analog input format 24 conv2 select analog input format 25 cos cos output 26 sin sin output 27C38 db12 to db1 (db1 = msb, db12 = lsb parallel input data) 41 v dd positive power supply 42 dgnd digital ground 44 busy internal logic setup time notes 1 90 orthogonal signals = sin q , cos q (resolver) = ph/ip4 and ph/ip1. 2 three phase, 120 , three-wire signals = cos q , cos ( q + 120 ), cos ( q + 240 ). = ph/ip1, ph/ip2, ph/ip3 high level = ph/iph1, ph/iph2, ph/iph3. 3 three phase, 120 , two-wire signals = cos ( q + 120 ), cos ( q + 240 ) = ph/ip2, ph/ip3. in all cases where any of the input pins 11 through 17 are not used, they must be left unconnected. pin configuration 6 5 4 3 2 1 44 43 42 41 40 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 v ss v dd strobe nc nc busy dgnd v dd nc nc v ss hpref hpop conv1 conv2 cos db12 hpfilt db11 nc = no connect. top view (not to scale) AD2S105 ph/op4 nc sin 7 8 11 12 13 14 15 16 17 9 10 nc db1 db2 db3 db4 db5 db6 db7 db8 db9 db10 ph/op1 nc nc agnd ph/ip4 ph/iph3 ph/ip3 ph/iph2 ph/ip2 ph/iph1 ph/ip1
AD2S105 rev. 0 C5C theory of operation a fundamental requirement for high quality induction motor drives is that the magnitude and position of the rotating air-gap rotor flux be known. this is normally carried out by measuring the rotor position via a position sensor and establishing a rotor oriented reference frame. to generate a flux component in the rotor, stator current is ap- plied. a build-up of rotor flux is concluded which must be maintained by controlling the stator current, i ds , parallel to the rotor flux. the rotor flux current component is the magnetizing current, i mr . torque is generated by applying a current component which is perpendicular to the magnetizing current. this current is nor- mally called the torque generating current, i qs . to orient and control both the torque and flux stator current vectors, a coordinate transformation is carried out to establish a new reference frame related to the rotor. this complex calcula- tion is carried out by the AD2S105. to expand upon the vector operator a description of a single vector rotation is of assistance. if it is considered that the moduli of a vector is op and that through the movement of ro- tor position by f , we require the new position of this vector it can be deduced as follows: let original vector op = a (cos u + jsin u ) where a is a constant; if oq = op e j f (1) and: e j f = cos f + jsin f oq = a (cos ( u + f ) + jsin ( u + f )) = a [ cos u cos f C sin u sin f + jsin u cos f + jcos u sin f ] = a [( cos u + jsin u ) ( cos f + j sin f )] (2) q f q + f q p o a d figure 1. vector rotation in polar coordinate the complex stator current vector can be represented as i s = i as + ai bs + a 2 i cs where a = e j 2 p 3 and a 2 = e j 4 p 3 . this can be re- placed by rectangular coordinates as i s = i ds + ji qs (3) in this equation i ds and i qs represent the equivalent of a two- phase stator winding which establishes the same magnitude of mmf in a three-phase system. these inputs can be seen after the three-phase to two-phase transformation in the AD2S105 block diagram. equation (3) therefore represents a three-phase to two-phase conversion. to relate these stator current to the reference frame the rotor currents assume the same rectangular coordinates, but are now rotated by the operator e j f , where e j f = cos f + jsin f . here the term vector rotator comes into play where the stator current vector can be represented in rotor-based coordinates or vice versa. the AD2S105 uses e j f as the core operator. in terms of the mathematical function, it rotates the orthogonal i ds and i qs com- ponents as follows: i ds ' + j i qs ' = ( i ds + ji qs ) e j f where i ds ', i qs ' = stator currents in the rotor reference frame. and e j f = cos f + jsin f = ( i ds + ji qs )( cos f + jsin f ) the output from the AD2S105 takes the form of: i ds ' = i ds cos f C i qs sin f i qs ' = i ds sin f + i qs cos f the matrix equation is: [ i ds ' ] = [ cos f C sin f ][ i ds ] i qs ' sin f cos f i qs and it is shown in figure 2. i ds i qs i ds ' i qs ' f e j f figure 2. AD2S105 vector rotation operation digital f latch 3 f to 2 f transformation latch latch sine and cosine multiplier (dac) sine and cosine multiplier (dac) park cos q cos q + 120 cos q + 240 sin q input clark cos ( q + f) sin ( q + f) figure 3. converter operation diagram
AD2S105 rev. 0 C6C analog signal input and output connections input analog signals all analog signal inputs to AD2S105 are voltages. there are two different voltage levels of three-phase (0 , 120 , 240 ) signal in- puts. one is the nominal level, which is 2.8 v dc or 2 v rms and the corresponding input pins are ph/ip1 (pin 17), ph/ip2 (pin 15), ph/ip3 (pin 13) and ph/ip4 (pin 11). the high level inputs can accommodate voltages from nominal up to a maximum of v dd /v ss . the corresponding input pins are ph/iph1 (pin 16), ph/iph2 (pin 14) and ph/iph3 (pin 12). the homopolar output can only be used in the three-phase connection mode. the converter can accept both two-phase format and three- phase format input signals. for the two-phase format input, the two inputs must be orthogonal to each other. for the three- phase format input, there is the choice of using all three inputs or using two of the three inputs. in the latter case, the third in- put signal will be generated internally by using the information of other two inputs. the high level input mode, however, can only be selected with three-phase/three-input format. all these different conversion modes, including nominal/high input level and two/three-phase input format can be selected using two se- lect pins (pin 23, pin 24). the functions are summarized in table i. table i. conversion mode selection conv1 conv2 mode description (pin 23) (pin 24) mode1 2-phase orthogonal with 2 inputs nc dgnd nominal input level mode2 3-phase (0 , 120 , 240 ) with 3 inputs dgnd v dd nominal/high input level* mode3 3-phase (0 , 120 , 240 ) with 2 inputs v dd v dd nominal input level *the high level input mode can only be selected with mode2. mode1: 2-phase/2 inputs with nominal input level in this mode, ph/ip1 and ph/ip4 are the inputs and the pins 12 through 16 must be left unconnected. mode2: 3-phase/3 inputs with nominal/high input level in this mode, either nominal or high level inputs can be used. for nominal level input operation, ph/ip1, ph/ip2 and ph/ip3 are the inputs, and there should be no connections to ph/iph1, ph/iph2 and ph/iph3; similarly, for high level input opera- tion, the ph/iph1, ph/iph2 and ph/iph3 are the inputs, and there should be no connections to ph/ip1, ph/ip2 and ph/ip3. in both cases, the ph/ip4 should be left unconnected. for high level signal input operation, select mode2 only. mode3: 3-phase/2 inputs with nominal input level in this mode, ph/ip2 and ph/ip3 are the inputs and the third signal will be generated internally by using the information of other two inputs. it is recommended that ph/ip1, ph/iph1, ph/iph2, ph/ip4 and ph/iph3 should be left unconnected. converter operation the architecture of the AD2S105 is illustrated in figure 3. the AD2S105 is configured in the forward transformation which ro- tates the stator coordinates to the rotor reference frame. vector rotation position data, f , is loaded into the input latch on the positive edge of the strobe pulse. (for detail on the timing, please refer to the timing diagram.) the negative edge of the strobe signi- fies that conversion has commenced. a busy pulse is subse- quently produced as data is passed from the input latches to the sin and cos multipliers. during the loading of the multiplier, the busy pulse remains high preventing further updates of f in both the sin and cos registers. the negative edge of the busy pulse signifies that the multipliers are set up and the orthogonal analog inputs are then multiplied real time. the resultant two outputs are accessed via the ph/op1 (pin 7) and ph/op4 (pin 6). for other configurations, please refer to transformation configuration. connecting the converter power supply connection the power supply voltages connected to v dd and v ss pins should be +5 v dc and C5 v dc and must not be reversed. pin 4 (v dd ) and pin 41 (v dd ) should both be connected to +5 v; similarly, pin 5 (v ss ) and pin 19 (v ss ) should both be con- nected to C5 v dc. it is recommended that decoupling capacitors, 100 nf (ceramic) and 10 m f (tantalum) or other high quality capacitors, are con- nected in parallel between the power line v dd , v ss and agnd adjacent to the converter. separate decoupling capacitors should be used for each converter. the connections are shown in fig- ure 4. AD2S105 top view 1 23 12 34 v dd v ss v ss v dd agnd 100nf 100nf 10 m f 10 m f + + +5v gnd ?v figure 4. AD2S105 power supply connection
AD2S105 rev. 0 C7C output analog signals there are two sets of analog output from the AD2S105. sin/cos orthogonal output signals are derived from the clark/ three-to-two-phase conversion before the park angle rotation. these signals are available on pin 25 (cos u ) and pin 26 (sin u ), and occur before park angle rotation. two-phase (sin ( u + f ), cos ( u + f )) signals these represent the output of the coordinate transformation. these signals are available on pin 6 (ph/op4, sin ( u + f )) and pin 7 (ph/op1, cos ( u + f )). homopolar output homopolar reference in a three-phase ac system, the sum of the three inputs to the converter can be used to indicate whether or not the phases are balanced. if v sum = ph/ip1 + ph/ip2 + ph/ip3 (or ph/iph1 + ph/ iph2 + ph/iph3) this can be rewritten as v sum = [cos u , + cos ( u + 120 ) + cos ( u + 240 )] = 0. any imbalances in the line will cause the sum v sum 1 0. the AD2S105 homopolar output (hpop) goes high when v sum > 3 v ts . the voltage level at which the hpop indicates an imbalance is determined by the hpref threshold, v ts . this is set internally at 0.5 v dc ( 0.1 v dc). the hpop goes high when v ts < ( cos q+ cos ( q+ 120 ) + cos ( q+ 240 )) 3 v where v is the nominal input voltage. with no external components v sum must exceed 1.5 v dc in order for hpop to indicate an imbalance. the sensitivity of the threshold can be reduced by connecting an external resistor be- tween hpop and ground in figure 5 where v ts = 0. 5 r ext r ext + 20,000 r ext is in w . 20k w 25 m a homopolar reference external resistor to trigger figure 5. the equivalent homopolar reference input circuitry example: from the equivalent circuit, it can be seen that the in- clusion of a 20 k w resistor will reduce v ts to 0.25 v dc. this corresponds to an imbalance of 0.75 v dc in the inputs. homopolar filtering the equation v sum = cos u + cos ( u + 120 ) + cos ( u + 240 ) = 0 denotes an imbalance when v sum 1 0. there are conditions, however, when an actual imbalance will occur and the condi- tions as defined by v sum will be valid. for example, if the first phase was open circuit when u = 90 or 270 , the first phase is valid at 0 v dc. v sum is valid, therefore, when cos u is close to 0. in order to detect an imbalance u has to move away from 90 or 270 , i.e., when on a balanced line cos u 1 0. line imbalance is detected as a function of hpref, either set by the user or internally set at 0.5 v dc. this corresponds to a dead zone when f = 90 or 270 30 , i.e., v sum = 0, and, therefore, no indicated imbalance. if an external 20 k w resistor is added, this halves v ts and reduces the zone to 15 . note this example only applies if the first phase is detached. in order to prevent this false triggering an external capacitor needs to be placed from hpfilt to ground, as shown in figure 5. this averages out the perceived imbalance over a complete cycle and will prevent the hpop from alternatively indicating balance and imbalance over u = 0 to 360 . for d q dt = 1000 rpm c ext = 220 nf d q dt = 100 rpm c ext = 2. 2 m f note: the slower the input rotational speed, the larger the time constant required over which to average the hpop output. use of the homopolar output at slow rotational speeds becomes im- practical with respect to the increased value for c ext . AD2S105 top view 1 23 12 34 agnd hpref hpop hpfilt 220nf dgnd c ext r ext hpop gnd hpref figure 6. AD2S105 homopolar output connections
AD2S105 rev. 0 C8C timing diagrams busy output the busy output will go hi at the negative edge of the strobe input. this is used to synchronize digital input data and load the digital angular rotation information into the device counter. the busy output will remain hi for 2 m s, and go lo until the next strobe negative edge occurs. strobe input the width of the positive strobe pulse should be at least 100 ns, in order to successfully start the conversion. the maxi- mum frequency of strobe input is 366 khz, i.e., there should be at least 2.73 m s from the negative edge of one strobe pulse to the next rising edge. this is illustrated by the following tim- ing diagram and table. t 1 t 2 t 3 t 4 strobe busy t f t r figure 7. AD2S105 timing diagram note: digital data should be stable 25 ns before and after posi- tive strobe edge. table ii. AD2S105 timing table parameter min typ max condition t 1 100 ns strobe pulse width t 2 30 ns strobe to busy - t 3 1.7 m s 2.5 m s busy pulse width t 4 100 ns busy to strobe - t r 20 ns busy pulse rise time with no load 150 ns busy pulse rise time with 68 pf load t f 10 ns busy pulse fall time with no load 120 ns busy pulse fall time with 68 pf load typical circuit configuration figure 8 shows a typical circuit configuration for the AD2S105 in a three phase, nominal level input mode (mode2). three phase input AD2S105 top view 141 38 30 27 23 12 16 digital angle input lsb sin cos 10 m f 100nf 10 m f 100nf ?v +5v gnd two phase output strobe busy hpop hpfilt hpref msb ph/op1 agnd ph/ip4 ph/ip3 ph/ip2 ph/ip1 34 figure 8. typical circuit configuration applications transformation configuration the AD2S105 can perform both forward and reverse transfor- mations. the section theory of operation explains how the chip operates with the core operator e +j f , which performs a for- ward transformation. the reverse transformation, e Cj f , is per- formed by providing a negative angle f . figure 9 shows two different phase input/output connections for AD2S105 reverse transformation operation. forward transformation AD2S105 reverse transformation AD2S105 e +j f 2 phase ?2 phase sin q cos q cos( q + f ) sin( q + f ) cos q sin q cos( q ? f ) sin( q ? f ) e ? f ? e +j f 3 phase ?2 phase cos q cos( q + 120 ) cos( q + 240 ) cos( q + f ) sin( q + f ) cos q cos( q + 120 ) cos( q + 240 ) cos( q ? f ) sin( q ? f ) e ? f figure 9. forward and reverse transformation connections
AD2S105 rev. 0 C9C measurement of harmonics in ac power systems, the quality of the electrical supply can be affected by harmonic voltages injected into the power main by loads, such as variable speed drive systems and computer power supplies. these harmonics are injected into other loads through the point of common coupling of the supply. this produces ex- tra losses in power factor correction capacitors, power supplies and other loads which may result in failure. it also can result in tripping and failure of computer systems and other sensitive equipment. in ac machines the resultant harmonic currents and flux patterns produce extra motor losses and torque pulsations, which can be damaging to the load. the AD2S105 can be used to monitor and detect the presence and magnitude of a particular harmonic on a three-phase line. figure 10 shows the implementation of such a scheme using the AD2S105, where va, vb, vc are the scaled line voltages. low pass filter park transformation 12-bit up/down counter AD2S105 a k homopolar output pulse inputs direction va vb vc three -to-two clark transformation vd vq vd 1 vq 1 e j f figure 10. harmonics measurement using AD2S105 selecting a harmonic is achieved by synchronizing the rotational frequency of the park digital input, f , with the frequency of the fundamental component and the integer harmonic selected. the update rate, r , of the counters is determined by: r = 4096 n w 2 p . here, r = input clock pulse rate (pulses/second); n = the order of harmonics to be measured; v = fundamental angular frequency of the ac signal. the magnitude of the n-th harmonic as well as the fundamental component in the power line is represented by the output of the low-pass filter, a k . in concert with magnitude of the harmonic the AD2S105 homopolar output will indicate whether the three figure 11. field oriented control of ac induction motors phases are balanced or not. for more details about this applica- tion, refer to the related application note listed in the bibliography. field oriented control of ac induction motors in ac induction motors, torque is produced through interaction between the rotating air gap field and currents induced in the rotor windings. the stator currents consist of two components, the flux component which drives the air gap field, and the torque component which is reflected from the rotor windings. a successful field oriented control strategy must independently control the flux component of current, referred to as direct cur- rent (i ds ), and the torque producing component of stator cur- rent, referred to as quadrature current (i qs ). the control architecture in figure 11 is referred to as field ori- ented because the control algorithms performed on the adsp- 2105 processor operate on decoupled flux and torque current components in a reference frame relative to the rotor flux of the motor. the control algorithms provide fast torque response at any speed which results in superior dynamic performance, and consequently, load variations have minimal effect on speed or position control. the ad2s90 resolver-to-digital converter is used to convert the modulated resolver position signals into a 12-bit digital position value. this value is brought into the adsp-2105 via the serial port where the control algorithms calculate the rotor flux angle. the rotor flux angle is the sum of the rotor position and the slip angle. the relationship between the stator current fre- quency and the slip frequency can be summarized by the follow- ing formula: f stat = ( v m ( p /2)) + f s lip where: f s tat = stator current frequency (hz) v m = mechanical speed of the motor ( revs/sec ) p = number of poles f s lip = slip frequency (hz) the rotor flux angle is fed into the 12-bit position input of the AD2S105. the AD2S105 transforms the three ac stator cur- rents using the digital rotor flux angle into dc values represent- ing direct current (i ds ) and quadrature current (i qs ). the transformation of the ac signals into dc values simplifies the de- sign of the a/d converter as it avoids the bandwidth sampling issues inherent in ac signal processing and in most cases elimi- nates the need for a simultaneous sampling a/d converter. adsp-2105 AD2S105 inv + pwm motor ad2s90 r / d converter resolver rotor position data rotor flux angle ids iqs i s2 i s3 i s1 2 channel 12 bit a/d converter sport rotor flux model stator current signals
AD2S105 rev. 0 C10C multiple pole motors for multi-pole motor applications where a single speed resolver is used, the AD2S105 input has to be configured to match the electrical cycle of the resolver with the phasing of the motor windings. the input to the AD2S105 is the output of a resolver- to-digital converter, e.g., ad2s80a series. the parallel output of the converter needs to be multiplied by 2 nC1 , where n = the number of pole pairs of the motor. in practice this is imple- mented by shifting the parallel output of the converter left rela- tive to the number of pole pairs. this will work for motors with a binary number of pole pairs. figure 12 shows the generic configuration of the ad2s80a with the AD2S105 for a motor with n pole pairs. the msb of the AD2S105 is connected to msbC(nC1) bit of the ad2s80a digi- tal output, msb-1 bit to msbC(nC2) bit, etc. msb msb-1 . . . msb ?(n?) . . . msb msb-1 msb-2 . . . . . . . . . . . ad2s80a AD2S105 12,14 or 16-bit resolution mode n = poles figure 12. a general consideration in connecting r/d converter and AD2S105 for multiple pole motors figure 13 shows the ad2s80a configured for use with a four pole motor, where n = 2. using the formula described the msb is shifted left once. ad2s80a AD2S105 bit1 bit2 . . . . . . bit13 bit14 msb msb-1 . . . . . . . lsb (msb) (lsb) 14-bit resolution mode . . . . . . figure 13. connecting of r/d converter ad2s80a and AD2S105 for four-pole motor application application notes list 1. vector control using a single vector rotation semicon- ductor for induction and permanent magnet motors, by f.p. flett, analog devices. 2. silicon control algorithms for brushless permanent mag- net synchronous machines, by f.p. flett. 3. single chip vector rotation blocks and induction motor field oriented control, by a.p.m. van den bossche and p.j.m. coussens. 4. three phase measurements with vector rotation blocks in mains and motion control, p.j.m. coussens, et al. 5. a tutorial in ac induction and permanent magnet synchronous motorsC vector-control with digital signal processors.
AD2S105 rev. 0 C11C outline dimensions dimensions shown in inches and (mm). 44-lead plastic leaded chip carrier (p-44a) 0.032 (0.81) 0.026 (0.66) 0.021 (0.53) 0.013 (0.33) 0.056 (1.42) 0.042 (1.07) 0.025 (0.63) 0.015 (0.38) 0.180 (4.57) 0.165 (4.19) 0.63 (16.00) 0.59 (14.99) 0.110 (2.79) 0.085 (2.16) 0.040 (1.01) 0.025 (0.64) 0.050 (1.27) bsc 0.656 (16.66) 0.650 (16.51) sq 0.695 (17.65) 0.685 (17.40) sq 0.048 (1.21) 0.042 (1.07) 0.048 (1.21) 0.042 (1.07) 40 6 top view 39 29 18 17 pin 1 identifier 7 28 0.020 (0.50) r
printed in u.s.a. c1938C18C7/94 C12C

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