Как управлять трехфазным двигателем с помощью ПЛК и ЧРП
Implementing automated control for industrial motors requires careful planning and execution. В этом подробном руководстве, we’ll walk through building a PLC-controlled three-phase motor system with VFD for bidirectional operation.
Project Overview
This industrial automation project enables:
- Smooth motor start/stop sequences
- Safe direction reversal
- Protective interlocks
- Programmable timing functions
All through the combined power of programmable logic controllers (ПЛК) и variable frequency drives (VFD).
Базовое введение в Power System
Required Components
To build this system, you’ll need:
Control Components
- PLC unit (Сименс, Аллен-Брэдли, etc.)
- VFD (2.2kW-5.5kW typical)
- Control relays (24VDC coil)
- Power contactors
Power Components
- Three-phase motor (matched to VFD rating)
- Circuit breakers (main and branch)
- Emergency stop buttons
- Selector switches
Wiring Essentials
- Control cables (shielded for VFD signals)
- Power cables (proper gauge)
- Terminal blocks
- DIN rail mounting
System Design & Wiring
Control Circuit Architecture
The intelligent backbone comprises:
- Operator inputs → PLC digital inputs
- PLC logic processing → Outputs to relays
- Relay contacts → Command VFD terminals
- VFD power stage → Drives motor
Critical Safety Features
- Electrical isolation between PLC and power circuits
- Physical interlocks on contactors
- Emergency stop hardwired to VFD enable
- Защита от перегрузки on all phases
PLC Programming Essentials
The control logic handles:
Motor Commands
NETWORK 1: Forward Run
IF "ForwardPB" AND NOT "ReversePB" THEN
"ForwardCmd" := TRUE;
END_IF;Protective Logic
- Direction interlock: Prevents simultaneous FWD/REV
- Start delay timer: 2-sec VFD pre-charge
- Safety cooldown: 5-sec post-stop lockout
VFD Configuration
Key parameter settings:
|
Параметр |
Setting |
Purpose |
|
P0.01 |
1 |
Terminal control |
|
P0.03 |
5Hz |
Start frequency |
|
P0.04 |
50Hz |
Base frequency |
|
P1.04 |
3с |
Acceleration time |
Testing Procedures
Validation Checklist
- Verify proper motor rotation direction
- Confirm forward/reverse interlocking
- Test emergency stop functionality
- Validate overload protection
- Check alarm conditions
Common Troubleshooting Tips
Motor Not Starting
- Check 24V control power
- Verify PLC outputs energizing
- Inspect VFD run command LED
Unexpected Direction Changes
- Validate wiring sequence (U-V-W)
- Check for crossed control wires
- Confirm interlock logic in program
Advanced Enhancements
Take your project further with:
- Modbus RTU communication between PLC-VFD
- Analog speed control via 0-10V input
- PID regulation for process control
- HMI integration for operator visualization
Final Thoughts
This PLC/VFD motor control solution delivers:
✅ Precise speed regulation
✅ Safe bidirectional operation
✅ Programmable automation
✅ Industrial reliability
For complex implementations, always consult local electrical codes and consider working with certified automation professionals.
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