# Frequently Asked Question

The maximum possible speed of the machines simulated by Typhoon HIL emulators depends on several factors that users have to take into account. These factors are ** machine speed feedback**,

**, and**

__electrical circuit fidelity__**. When the user estimates all speed limits enforced by these factors, the lowest of the three provides us with the maximum speed the machine can reach during simulation. Below you can find guidelines on how to estimate the maximum speed limit imposed by these factors. Keep in mind that these factors are not relevant for SP-based electrical machines:**

__firmware limit____Machine speed feedback__

__Machine speed feedback__

**Encoder feedback**- If your C-HIL application is utilizing Encoder signal feedback for speed estimation, it is necessary to make sure that these signals are generated with proper fidelity. This fidelity depends on several factors: encoder pulses per revolution, maximum rotor mechanical frequency, and simulation time step. The formula that validates that the fidelity of the encoder signals is proper, can be found on each machine documentation page in the Paragraph
__Feedback__, but is also presented here: where is encoder pulses per revolution, is rotor mechanical frequency, and is simulation time step. - Example:
- If your encoder has 1024 encoder pulses per revolution, and the model is simulated with 1uS, the maximum rotor mechanical frequency ис 244.14 Hz, which is 1533.98 rad/s or 14648.4 RPM

- If your C-HIL application is utilizing Encoder signal feedback for speed estimation, it is necessary to make sure that these signals are generated with proper fidelity. This fidelity depends on several factors: encoder pulses per revolution, maximum rotor mechanical frequency, and simulation time step. The formula that validates that the fidelity of the encoder signals is proper, can be found on each machine documentation page in the Paragraph
**Resolver feedback**- The Resolver feedback system generates two sinusoidal output signals, which encode the mechanical angle of the shaft. Both of these signals are generated using carrier signal which for C-HIL application can be provided externally to the machine model
*(through analog inputs)*or internally*(from the model)*. The resolver system is inherently designed in a way where the frequency of the resolver carrier signal is several times larger than the maximal rotational frequency of the machine. This means that during the estimation of the maximal rotational frequency of the machine, it is necessary only to compare the simulation time step of the model and the period of the carrier signal of the resolver. It is recommended that his ratio is at least ten times, where the__period of the carrier signal should be at least 10 times larger than the simulation time step__.

- The Resolver feedback system generates two sinusoidal output signals, which encode the mechanical angle of the shaft. Both of these signals are generated using carrier signal which for C-HIL application can be provided externally to the machine model

__Electrical circuit fidelity__

__Electrical circuit fidelity__

- For proper simulation of the electrical machines, it is necessary to preserve the fidelity of electrical circuit waveforms. The frequency of these waveforms depends on the type of the machine and the number of pole pairs - for the induction machine, the electrical waveforms revolve around the synchronous frequency of the machine, depending on the operational mode, while for the synchronous machines, frequency is directly proportional to the rotational frequency. For simplicity reasons, we'll assume that the electrical waveforms of the machine are directly proportional to mechanical rotational frequency, regardless of the machine type.
- The relationship between the frequency of the electrical waveforms and rotor mechanical frequency is expressed with the number of pole pairs, or , where is the frequency of electrical waveforms in the machines, while
- For adequate fidelity, it is recommended that the following equation is fulfilled: , where is the simulation time step,
*p*is the number of pole pairs of the machine while is rotor mechanical frequency. - It is important to understand that electrical circuit fidelity depends on many other factors, such as power electronic converters connected to the machine, the electrical circuit that the machine consists of, etc. Therefore the proposed condition does not guarantee that the machine will be stable and capable of simulating with a given speed, but is just a recommendation which should be validated on the model and adjusted if proven unstable.
- Example:
- If the simulation time step is 1uS and the number of pole pairs is 8, the maximum mechanical rotational frequency is 1250 Hz or 7853 rad/s

__Firmware limit__

__Firmware limit__

- On top of the aforementioned two conditions based on either the feedback system of the machine or the electrical circuit simulation capability, there is a third condition imposed by firmware capabilities. This firmware allows
**the**, regardless of the machine type, electrical, or feedback parameters. This limit is introduced from THCC 2024.2, while before it, the limit was 10000rad/s.__maximum mechanical speed of the machine to be 20000 rad/s__