VESC Inverter Sound Simulator

This project simulates the switching pattern sound of arbitrary traction inverters on a VESC (Vedder Electronic Speed Controller) using SPWM (Sinusoidal Pulse Width Modulation) techniques. Please note that this project does not change the actual pulse pattern generated by the inverter, but rather attempts to simulate the sounds generated by the inverter with a minimal effect on the torque output of the motor.

NOTE: Currently, this project causes motor control instabillity at higher speeds - either don't use it at higher speeds, or wait until I've figured out how to solve this issue.

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Table of Contents

• Installation
• Usage
• Configuration
• Example Configurations
• Important Notes
• Contributing
• License

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Installation

Prerequisites

• A VESC with firmware that supports custom C code.
• A compatible development environment (e.g., VESC Tool, VESC firmware source code).
• Basic knowledge of compiling and flashing firmware to the VESC.

Steps

1. Clone the Repository:

   git clone https://github.com/yourusername/vesc-inverter-sound-simulator.git
   cd vesc-inverter-sound-simulator

2. Build the Code:

   • Ensure you have the necessary toolchain installed (e.g., gcc-arm-none-eabi).
   • Run the build script:

     ./Build.py

   • This will compile the C code and generate a Lisp binary (VVVF_COMPILED.lisp) that can be loaded onto the VESC.

3. Load the Lisp Code:

   • Open the VESC Tool and connect to your VESC.
   • Go to the "LispBM" tab and load the VVVF_COMPILED.lisp file.

4. Stream or Upload:

   • Use either the stream or upload button to push the LispBM script to your VESC.

Configuration

Unfortunately due to memory limitations the parameters are hardcoded, I tried to use JSON but there was not enough RAM on the STM32 for that to work. So, you'll have to write the code in C and compile it.

General Parameters

The behavior of the inverter sound simulation can be fine-tuned by modifying the following parameters in the Parameters.h file:

Wheel and Speed Settings

• WHEEL_DIAMETER_MM: The diameter of the wheel in millimeters. This is used to calculate the speed in km/h based on the motor's RPM.

  #define WHEEL_DIAMETER_MM 550  // Example: 550mm wheel diameter

• MAX_SPEED_KMH: The maximum speed (in km/h) that the inverter sound simulation will support. Speeds above this value will be capped.

  #define MAX_SPEED_KMH 100  // Example: Maximum speed of 100 km/h

• MAX_SPEED_RANGES: The maximum number of speed ranges that can be configured. Each range defines a different SPWM behavior.

  #define MAX_SPEED_RANGES 16  // Example: Up to 16 speed ranges

Sample Rate

• SAMPLE_RATE: The sample rate for the audio generation. This should match the FOC (Field-Oriented Control) zero vector frequency of your VESC.

  #define SAMPLE_RATE 25000  // Example: 25kHz sample rate

Inverter Cutoff

• ZERO_CUTOFF_MARGIN_KMH: The speed (in km/h) below which the inverter sound will be disabled when slowing down. This prevents the inverter sound from playing at very low speeds.

  #define ZERO_CUTOFF_MARGIN_KMH 1  // Example: Disable inverter sound below 1 km/h

Current Ramp Settings

• INVERTER_CURRENT_RAMP_START: The minimum motor current (in amps) at which the inverter sound starts ramping up.

  #define INVERTER_CURRENT_RAMP_START 3.0  // Example: Start ramping at 3A

• INVERTER_CURRENT_RAMP_END: The maximum motor current (in amps) at which the inverter sound reaches its full amplitude.

  #define INVERTER_CURRENT_RAMP_END 120.0  // Example: Full amplitude at 120A

Amplitude Ramp Settings

• INVERTER_AMPLITUDE_RAMP_START: The minimum amplitude (in volts) of the inverter sound when the motor current is at INVERTER_CURRENT_RAMP_START.

  #define INVERTER_AMPLITUDE_RAMP_START 0.00  // Example: Start with 0V amplitude

• INVERTER_AMPLITUDE_RAMP_END: The maximum amplitude (in volts) of the inverter sound when the motor current is at INVERTER_CURRENT_RAMP_END.

  #define INVERTER_AMPLITUDE_RAMP_END 0.35  // Example: Max amplitude of 0.35V

Speed-Based Amplitude Scaling

• INVERTER_AMPLITUDE_SPEED_RAMP_START_KMH: The speed (in km/h) at which the amplitude scaling starts.

  #define INVERTER_AMPLITUDE_SPEED_RAMP_START_KMH 15.0  // Example: Start scaling at 15 km/h

• INVERTER_AMPLITUDE_SPEED_RAMP_END_KMH: The speed (in km/h) at which the amplitude scaling reaches its maximum.

  #define INVERTER_AMPLITUDE_SPEED_RAMP_END_KMH 40.0  // Example: Full scaling at 40 km/h

• INVERTER_AMPLITUDE_SPEED_SCALAR_START: The starting scalar value for amplitude scaling at INVERTER_AMPLITUDE_SPEED_RAMP_START_KMH.

  #define INVERTER_AMPLITUDE_SPEED_SCALAR_START 1.0  // Example: Start with 1.0x scaling

• INVERTER_AMPLITUDE_SPEED_SCALAR_END: The ending scalar value for amplitude scaling at INVERTER_AMPLITUDE_SPEED_RAMP_END_KMH.

  #define INVERTER_AMPLITUDE_SPEED_SCALAR_END 2.0  // Example: End with 2.0x scaling

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Example Configuration

Here’s an example configuration for a typical setup:

#define WHEEL_DIAMETER_MM 550
#define MAX_SPEED_KMH 100
#define MAX_SPEED_RANGES 16
#define SAMPLE_RATE 25000
#define ZERO_CUTOFF_MARGIN_KMH 1
#define INVERTER_CURRENT_RAMP_START 3.0
#define INVERTER_CURRENT_RAMP_END 120.0
#define INVERTER_AMPLITUDE_RAMP_START 0.00
#define INVERTER_AMPLITUDE_RAMP_END 0.35
#define INVERTER_AMPLITUDE_SPEED_RAMP_START_KMH 15.0
#define INVERTER_AMPLITUDE_SPEED_RAMP_END_KMH 40.0
#define INVERTER_AMPLITUDE_SPEED_SCALAR_START 1.0
#define INVERTER_AMPLITUDE_SPEED_SCALAR_END 2.0

This configuration is designed for a 550mm wheel, with a maximum speed of 100 km/h, and amplitude scaling based on both motor current and speed. Adjust these values to match your specific motor and pev setup.

Switching Pattern Configuraiton

The inverter sound simulation can be configured by modifying the ConfigParser.c file. The configuration is divided into speed ranges, each with its own SPWM (Sinusoidal Pulse Width Modulation) settings.

Speed Ranges

Each speed range defines the behavior of the inverter sound within a specific speed range (in km/h). You can configure the following parameters for each range:

• SPWM Type:

  • SPWM_TYPE_FIXED_ASYNC: Fixed frequency asynchronous SPWM.
  • SPWM_TYPE_RAMP_ASYNC: Ramp frequency asynchronous SPWM.
  • SPWM_TYPE_RSPWM: Random SPWM.
  • SPWM_TYPE_SYNC: Synchronous SPWM.
  • SPWM_TYPE_NONE: Disable inverter sound.

• Carrier Frequency: The frequency of the carrier wave used in SPWM.

• Number of Pulses: For synchronous SPWM, the number of pulses per cycle.

Example Configuration

Here’s an example configuration that defines three speed ranges:

void InitializeConfiguration(InverterConfig* _Config) {
    _Config->maxSpeed = MAX_SPEED_KMH; // km/h
    _Config->rpmToSpeedRatio = wheel_diameter_to_kmh_factor(WHEEL_DIAMETER_MM);
    _Config->zeroSpeedCutoffMargin = ZERO_CUTOFF_MARGIN_KMH;

    // Add speed ranges
    AddSPWM_AsyncFixed(_Config, 0, 0., 22.0, 1000); // Async SPWM from 0-22 km/h @ 1kHz carrier
    AddSPWM_AsyncRamp(_Config, 1, 22.0, 44.0, 1000, 2000); // Async SPWM from 22-44 km/h @ 1kHz-2kHz carrier
    AddSPWM_Sync(_Config, 2, 44.0, 9999.0, 12); // Sync SPWM from 44 km/h and above with 12 pulses
}

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Example Switching Pattern Configurations

Fixed Frequency Async SPWM

This configuration uses a fixed carrier frequency for all speeds:

AddSPWM_AsyncFixed(_Config, 0, 0., 9999.0, 1000); // Fixed 1kHz carrier for all speeds

Ramp Frequency Async SPWM

This configuration ramps the carrier frequency from 1kHz to 2kHz as speed increases:

AddSPWM_AsyncRamp(_Config, 0, 0., 50.0, 1000, 2000); // Ramp from 1kHz to 2kHz between 0-50 km/h

Random SPWM

This configuration uses random carrier frequencies within a range:

AddSPWM_RSPWM(_Config, 0, 0., 50.0, 1000, 5000); // Random carrier frequency between 1kHz and 5kHz

Synchronous SPWM

This configuration uses synchronous SPWM with a fixed number of pulses:

AddSPWM_Sync(_Config, 0, 0., 9999.0, 12); // 12 pulses per cycle for all speeds

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Important Notes

1. Avoid Modifying the Lisp Code:

   • The Lisp code (VVVF_COMPILED.lisp) is automatically generated from the C code. Do not modify the Lisp code directly, your changes will be overwritten when you recompile! Instead, make your changes in the C code and recompile using the Build.py script. If you need to modify the lisp code, use the file Main.lisp in the Lisp directory.

2. Motor Stuttering Issues:

   • Low Frequencies: Using carrier frequencies that are too low can cause large hub motors (e.g., QS205) to stutter. Ensure the carrier frequency is high enough to avoid this issue.
   • High Amplitude: Setting the amplitude too high can also cause stuttering. Start with a low amplitude and gradually increase it while monitoring motor performance.

3. Amplitude and Frequency Tuning:

   • Experiment with different carrier frequencies and amplitudes to find the optimal settings for your motor. Larger motors may require higher frequencies and lower amplitudes to avoid stuttering.

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Contributing

Contributions are welcome! If you have any improvements, bug fixes, or new features, feel free to open a pull request. Please ensure your code follows the existing style and includes appropriate documentation.

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License

This project is licensed under the GPLv3 License. See the LICENSE.md file for details.

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Enjoy simulating inverter sounds on your VESC! If you have any questions or run into issues, feel free to open an issue on GitHub.

Contact

If you have questions or need assistance, you can find me over at my website.