Inverter Drive Simulator

This is a desktop app, written to simulate a variable frequency drive (VFD) controlling an induction motor. It provides a user interface for configuring motor and drive parameters, simulating input signals, monitoring motor behavior, injecting faults, and visualizing real-time plots.

Application Structure

The simulator is organized into modular C files, each handling specific functionality:

• main.c: Initializes the GTK application, sets the dark theme (gtk-application-prefer-dark-theme), and activates the main window.
• gui.c/h: Manages the GUI layout using a GtkGrid with controls on the left (motor parameters, drive settings, input signals, control panel, fault inputs, outputs) and plots on the right (voltage, current, frequency, torque, speed).
• inverter.c/h: Handles inverter calculations, including line-to-line voltage (V_L-L) and PWM waveform generation.
• motor.c/h: Simulates an induction motor with V/f control, calculating speed, torque, current, and temperature.
• fault.c/h: Detects and manages faults (overcurrent, undervoltage, overtemperature) with manual injection and reset capabilities.
• waveform.c/h: Renders five real-time plots using GtkDrawingArea and Cairo, currently displaying a placeholder voltage waveform for all parameters.

GUI Layout

The GUI is divided into two main sections within a GtkGrid:

• Left Columns (0–3):
  • Status Label: Displays "Running", "Stopped", or "Faulted" with direction (Forward/Reverse).
  • Motor Parameters: Text entries for rated voltage (V), current (A), frequency (Hz), and RPM.
  • Drive Settings: Entries for ramp up/down times (s), max/min frequency (Hz), and a combo box for control mode (V/f only, with placeholders for vector control, sensorless vector, DTC).
  • Input Signals: Slider for speed reference (0–100%), Forward/Reverse buttons.
  • Control Panel: Run, Stop, Reset buttons, and a keypad entry for parameter updates (currently sets rated voltage).
  • Fault Inputs: Checkboxes for manual fault injection (overcurrent, undervoltage, overtemperature).
  • Output Labels: Show calculated V_L-L, current, speed, torque, frequency, and fault/error messages.
• Right Column (4):
  • Plot Area: Five stacked plots (voltage, current, frequency, torque, speed) rendered with Cairo, each with a grid, waveform, and label.

The dark theme ensures a dark background with light text and bright plot colors (blue waveform, light gray grid).

Simulation Logic

The simulation runs in a timed loop (50 ms interval) triggered by the "Run" button and managed in gui.c (update_simulation function).

Key steps include:

1. Input Collection:

   • Reads motor parameters, drive settings, speed reference, and fault checkboxes from GUI widgets.
   • Parameters: Rated voltage (1–10,000 V), current (1–1,000 A), frequency (1–1,000 Hz), RPM (1–10,000), ramp up/down (0–60 s), max/min frequency (0–1,000 Hz, min ≤ max).
   • Speed reference: Slider value (0–100%) scales to max frequency.

2. Input Validation:

   • Checks for valid ranges (e.g., rated_voltage > 0, max_freq > min_freq).
   • Displays error messages in the error label (e.g., "Invalid Rated Voltage (1–10000 V)") and stops simulation if invalid.

3. Motor and Inverter Update:

   • Updates motor parameters (motor.c: set_motor_params) and drive settings (set_drive_params).
   • Sets inverter parameters (inverter.c: set_inverter_params) with rated voltage, target frequency (from speed reference), and fixed modulation index (0.8).
   • Updates motor state (update_motor) with target frequency, direction, and ramp times.

4. Fault Handling:

   • Checks automatic faults (fault.c: check_faults) based on thresholds: current > 20 A, voltage < 300 V, temperature > 80°C.
   • Applies manual faults if checkboxes are active (trigger_fault).
   • Stops simulation and updates status/error labels if a fault occurs.

5. Output Calculation:

   • Calculates V_L-L (calculate_vll), motor current, speed, torque, and frequency (get_motor_* functions).
   • Updates output label with formatted values (e.g., "V_L-L: 392.30 V\nCurrent: 8.00 A\n...").
   • Queues plot redraw (gtk_widget_queue_draw).

6. Plot Rendering:

   • Draws five plots in waveform.c (draw_waveform), each with a grid, waveform, and label.
   • Currently uses a placeholder voltage waveform (get_pwm_waveform) scaled to max values (e.g., 1.1 * V_dc for voltage).

The simulation stops when:

• "Stop" button is clicked (is_running = FALSE).
• A fault is detected or injected (has_fault()).
• Invalid inputs are entered.

The "Reset" button clears faults, unchecks fault boxes, and updates the status.

Key Calculations

The simulator uses simplified models for inverter and motor behavior, focusing on V/f control. Below are the main calculations:

Inverter Calculations (inverter.c)

• Line-to-Line Voltage (V_L-L):
  • Formula: V_L-L = m_a * V_dc * sqrt(3) / sqrt(2)
  • m_a (modulation index) is fixed at 0.8.
  • V_dc is the rated voltage from motor parameters.
  • Example: For V_dc = 400 V, V_L-L = 0.8 * 400 * sqrt(3) / sqrt(2) ≈ 392.30 V.
• PWM Waveform:
  • Generates a sinusoidal waveform: V(t) = m_a * V_dc * sin(2π * freq * t).
  • freq is the target frequency (speed reference * max frequency).
  • Samples: 100 points over one period (1/freq).

Motor Calculations (motor.c)

• Speed:
  • Target speed: (target_freq / rated_freq) * rated_rpm * (is_forward ? 1 : -1).
  • Applies ramping: Acceleration = rated_rpm / ramp_up, deceleration = rated_rpm / ramp_down.
  • Updates every 50 ms: current_speed += accel * 0.05 or -decel * 0.05, clamped to target.
  • Example: For target_freq = 50 Hz, rated_freq = 50 Hz, rated_rpm = 1500, speed = 1500 RPM (forward).
• Frequency:
  • Derived from speed: current_freq = |current_speed / rated_rpm| * rated_freq.
• Torque:
  • Simplified (constant torque load): torque = rated_current * rated_voltage / rated_rpm * |current_speed|.
  • Example: For rated_current = 10 A, rated_voltage = 400 V, rated_rpm = 1500, speed = 1500 RPM, torque ≈ 106.67 Nm.
• Current:
  • Proportional to frequency: current = rated_current * (current_freq / rated_freq).
  • Example: For current_freq = 40 Hz, rated_freq = 50 Hz, rated_current = 10 A, current = 8 A.
• Temperature:
  • Increases with current: temp += current * 0.01 per cycle, minimum 25°C (ambient).
  • Example: For current = 10 A, temp increases by 0.1°C every 50 ms.

Fault Detection (fault.c)

• Overcurrent: Triggered if current > 20 A.
• Undervoltage: Triggered if voltage < 300 V.
• Overtemperature: Triggered if temp > 80°C.
• Manual faults override automatic checks when checkboxes are active.

Parameters

The application handles the following user-configurable parameters, validated in gui.c:

Parameter	Range	Default	Description
Rated Voltage (V)	1–10,000	400	Motor rated voltage (V_dc for inverter).
Rated Current (A)	1–1,000	10	Motor rated current.
Rated Frequency (Hz)	1–1,000	50	Motor rated frequency.
Rated RPM	1–10,000	1500	Motor rated speed.
Ramp Up Time (s)	0–60	2	Time to reach rated speed.
Ramp Down Time (s)	0–60	2	Time to stop from rated speed.
Max Frequency (Hz)	0–1,000 (> min)	100	Maximum output frequency.
Min Frequency (Hz)	0–max_freq	10	Minimum output frequency.
Speed Reference (%)	0–100	50	Scales target frequency (min to max).
Control Mode	V/f (others N/A)	V/f	Motor control mode (V/f implemented).
Direction	Forward/Reverse	Forward	Motor rotation direction.
Faults (Overcurrent, etc.)	On/Off	Off	Manual fault injection.
Keypad Value	Any number	N/A	Updates rated voltage (simplified).

Simulation Characteristics

• Input Signals:
  • Speed reference slider scales target frequency (speed_ref * max_freq / 100).
  • Forward/Reverse buttons toggle motor direction (is_forward).
  • Run/Stop/Reset buttons control simulation state and fault clearing.
• Motor Behavior:
  • V/f control: Voltage and frequency are proportional (V/f = constant).
  • Ramps speed based on user-defined ramp times.
  • Simulates constant torque load (simplified).
• Graphical Monitoring:
  • Five plots (600x600 pixels total, 80 pixels per plot) show voltage, current, frequency, torque, and speed.
  • Placeholder: All plots use the PWM voltage waveform scaled to max values (e.g., 1.1 * V_dc for voltage).
• Fault Handling:
  • Automatic detection based on thresholds.
  • Manual injection via checkboxes.
  • Faults stop simulation and display status (e.g., "Fault: Overcurrent").
• Control Panel:
  • Replicates a VFD panel with Run, Stop, Reset, Forward/Reverse buttons.
  • Keypad entry simulates parameter editing (limited to voltage).