How to set particle emission rate at run time?

https://blogs.unity3d.com/2016/04/20/particle-system-modules-faq/

Well, I'm a bit late (3 years) BUT, because I was in the situation, I have a solution! Basically, you have to manually emit the number of particle you want and disable the particle generation beforehand.
(Rate over Time = 0)

In my example, I want to set the number of particles according to my speed :

 using UnityEngine;
 
 public class ExempleParticuleSetter : MonoBehaviour
 {
     private ParticleSystem particleSystem;
     //In my exemple, x = min & y = max
     [SerializeField] private Vector2 minMaxEmmiter = new Vector2(0,80);
     [SerializeField] private Vector2 minMaxSpeedDesire = new Vector2(80,200);
 
     //Other variable I need
     private Rigidbody rb;
 
     private void Start()
     {
         particleSystem = GetComponentInChildren<ParticleSystem>();
         
         rb = GetComponent<Rigidbody>();
     }
 
     private void Update()
     {
         //Get the number of particle to emit by some little calculation
         var speed = rb.velocity.magnitude;
         var t = (speed - minMaxSpeedDesire.x) / (minMaxSpeedDesire.y);
         var particleToEmit = (int) Mathf.Lerp(minMaxEmmiter.x, minMaxEmmiter.y, t);

         //Here I Emit my particle
         particleSystem.Emit(particleToEmit);
     }
 }