Rate Limiter with variable slew rate

Hello, I need a Rate Limiter with variable slew rate in my Simulink model. Simulink library contains block Rate Limiter Dynamic but it runs only with fixed step solver. I use ode15s solver in my simulations. But I can't use fixed step solver because simulation then dramatically slows down.

So I tried to use Rate Limiter block from library and set Risign Slew Rate and Falling Slew Rate parameters of this block during simulation. I do it through a Matlab function block which executes this code:

 ChangeSlewRate(u)
 %#codegen

 eml.extrinsic('get_param');
 eml.extrinsic('set_param');
 eml.extrinsic('num2str');

 subsystemFullPath = 'MUV74_model/DesiredPowerRate;
 blockName = [subsystemFullPath '/Rate Limiter'];
 if (u > 0) % do not limit slew rate
    set_param(blockName,'risingSlewLimit',num2str(inf));
    set_param(blockName,'fallingSlewLimit',num2str(-inf));
 else   % set preddefined slew rate limits
    risingSlewRate = get_param(subsystemFullPath,'RS');
    fallingSlewRate = get_param(subsystemFullPath,'FS');
    set_param(blockName,'risingSlewLimit',risingSlewRate);
    set_param(blockName,'fallingSlewLimit',fallingSlewRate);
 end

Where RS and FS are dialog parameters of DesiredPowerRate subsystem that contains Rate Limiter block and u is inputof DesiredPowerRate subsystem which depends rate change on. It runs very well but speed of simulation drops dramatically down. After reading some articles I realized that implementation of code in C MEX S-function will be probably faster.

My question is: How to set parameters of Rate Limiter block from C MEX S-function ? Will the simulation be faster ? Any other ideas how to do it better ?

Thank you

Answer 1

[Sachin Ganjare]

You can use the 'Acceleration' mode for simulation, which will generate code & mex file automatically, along with improvement in execution speed drastically.

Hope this helps!!!!!!!!