I just did a quick test and I believe this configuration is what you're looking for:

1. Set up the CHW loop as shown in the picture below
   • Put a bypass Pipe:Adiabatic on the demand side.
   • Put aPump:VariableSpeed on the supply side.
2. In the Chiller:Electric:EIR
   • Set the 'Chiller Flow Mode' to 'NotModulated'
3. In the PlantLoop
   • Set the 'Minimum Loop Flow' rate to your minimum. For my test I arbitrarily picked 240 gpm, which was 20% of the loop design flow rate.
4. In the Pump:VariableSpeed
   • Set the 'Minimum Flow Rate' rate to your minimum
   • Set the 'Pump Control Type' to intermittent (the pump shuts off when there is no demand on the loop)

Here's the result (sorry the pictures are so small):

At Point A, the Chiller (black, top) is running and the pump (red, bottom) is pumping above the minimum flow rate but there's no flow through the bypass (orange, bottom).

At Point B, the Chiller (black, top) is running at a lower power. The pump (red, bottom) is pumping at the minimum flow rate even though the coils aren't calling for flow. Whatever the coils don't need flows through the bypass (orange, bottom).

In this plot of CHW pump and CHW bypass vs. Chiller part load, you can see that when the chilled water pump (red) is above the minimum flow (horizontal black line), there is barely ever any flow through the bypass (orange). However, when the chilled water pump is at minimum flow, there is often lots of flow through the bypass, with the bypass flow topping out at the minimum CHW flow rate.

I just did a quick test and I believe this configuration is what you're looking for:

1. Set up the CHW loop as shown in the picture below
   • Put a bypass Pipe:Adiabatic on the demand side.
   • Put aPump:VariableSpeed on the supply side.
2. In the Chiller:Electric:EIR
   • Set the 'Chiller Flow Mode' to 'NotModulated'
3. In the PlantLoop
   • Set the 'Minimum Loop Flow' rate to your minimum. For my test I arbitrarily picked 240 gpm, which was 20% of the loop design flow rate.
4. In the Pump:VariableSpeed
   • Set the 'Minimum Flow Rate' Loop Flow' rate to your minimum
   • Set the 'Pump Control Type' to intermittent (the pump shuts off when there is no demand on the loop)

Here's the result (sorry the pictures are so small):

At Point A, the Chiller (black, top) is running and the pump (red, bottom) is pumping above the minimum flow rate but there's no flow through the bypass (orange, bottom).

At Point B, the Chiller (black, top) is running at a lower power. The pump (red, bottom) is pumping at the minimum flow rate even though the coils aren't calling for flow. Whatever the coils don't need flows through the bypass (orange, bottom).

In this plot of CHW pump and CHW bypass vs. Chiller part load, you can see that when the chilled water pump (red) is above the minimum flow (horizontal black line), there is barely ever any flow through the bypass (orange). However, when the chilled water pump is at minimum flow, there is often lots of flow through the bypass, with the bypass flow topping out at the minimum CHW flow rate.