The application with servo control comprehensive system is made in machine tool of industrial robot, numerical control, electron, the domain such as machinery of printing machine instrument, spin, main effect is produced in industrial production. The domain waits in industrial robot and numerical control machine tool, answer speed fast, torsion shakes the servo control system with Xiaohe expensive precision is more and more crucial. Of servo control system comprise by positional annulus, speed annulus and voltaic annulus, voltaic annulus is core, the precision that the function of voltaic annulus decided whole control system and answer speed.

 

A factor that affects voltaic annulus performance is voltaic sampling means, at present the voltaic sampling means of the mainstream includes sampling of suddenly Er electric current, segregation to carry discharge sheds sampling and segregation Δ-ΣSampling of modulator electric current. The segregation Δ- of TIΣGrade of tall, insulation mixes the precision of modulator AMC1305 high interference rejection performance is strong, apply extensively in the domain such as industrial servo, transducer and solar energy inverter.

 

The voltaic sampling means of AMC1305 is shown 1 times like the graph, AMC1305 sheds voltaic information changeover for single-track data, this data flows to wait for the filter module in dominating chip through DSP, reductive get voltaic information. Compare at means of sampling of before two kinds of electric current, keep apart Δ-ΣModulator is used at voltaic sampling, have precision to be mixed high the good point with interference rejection strong capability. But, keep apart Δ-ΣThe bandwidth of the voltaic sampling means of modulator is low, answer speed slow, when electric machinery overload or short circuit, need longer time ability to be mirrorred on voltaic number amount, possible meeting creates protective be no longer in force.

 

 

Graph 1: The voltaic sampling sketch map of AMC1305

 

To promote the sampling of AMC1305 electric current the property of means, annulus of electric current of give attention to two or morethings is controlled and shed protective function too, can be in the controller such as DSP, install filter of two groups of numbers (see a picture 2) , one group has inferior bandwidth and taller precision, use at control of annulus of in-house electric current; Additionally one group, have taller bandwidth and inferior precision, use at shedding protection too.

 

 

 

Graph 2: The means of control of annulus of electric current of a kind of give attention to two or morethings and the voltaic sampling filter that shed protective function too

 

The voltaic sampling means of use AMC1305, use Sinc3 filter to collect voltaic information normally, of Sinc3 filter cross sampling to lead (Over Sample Rate, OSR) the precision that decided voltaic sampling and bandwidth (see a picture 3) . Use similar filter structure, OSR and filter frequency answer the 3 that be like a graph (A) be shown, OSR is bigger, bandwidth is lower. Below similar filter structure, the effective digit below different OSR (ENOB) if pursue 3 (B) be shown, OSR is bigger, ENOB is bigger.

 

 

 

 

Graph 3: The OSR of Sinc3 filter, bandwidth and effective a relation

 

AMC1305 is used at voltaic sampling, use Sinc3 filter, different OSR, if the bandwidth of voltaic sampling and ENOB express 1 to show.

 

Express 1: The OSR of Sinc3 filter, bandwidth and effective a relation

 

 

 

 

Pass above analysis, voltaic be surrounded by mountains is tall to precision requirement, the OSR setting of Sinc3 filter is 128 or 256, ENOB is more than 13; Shed protection too the function is tall to fast sex requirement, the OSR setting of Sinc3 filter is 8 or 16, answer bandwidth to be more than 330kHz.

 

The article puts forward a kind of improvement segregation Δ-ΣThe plan of means of sampling of modulator electric current, this plan has the following advantage:

 

When ● was satisfying high accuracy of voltaic annulus pilot to ask, had satisfied the fast sex requirement that sheds protection;

● implementation is simple, need not alter exterior circuit