Getting vfd torque control right is the difference between a smooth winding process and a snapped web. If your torque mode setup is off, the motor either stalls under load or over-accelerates, ruining your material. On our production line here at SHZK, we test every 300N series drive under full load before it ships. I’ve seen firsthand how tweaking the P2 parameters transforms a shaky application into a rock-solid tension control system. This guide breaks down exactly how to configure the SHZK 300N for torque mode, using real parameter numbers straight from our engineering floor.
When to Use Torque Control Instead of Speed Control
Standard speed control works fine for conveyors and fans. But when your application requires a specific pulling force regardless of the speed, you need to switch to torque mode. We see this constantly in winding, unwinding, and hoisting applications. The variable-frequency drive shifts from regulating RPM to regulating the motor’s magnetic flux and current to maintain a strict torque output.
The Physics of the Setup
In torque mode, the VFD ignores the standard speed reference. Instead, it uses a torque reference. The motor will accelerate or decelerate until the load matches the requested torque, or until it hits the speed limit you set. If you don’t cap the speed, an unloaded motor in torque mode will literally run away and destroy itself. Setting the maximum speed limit and the torque upper limit is your first critical step.
Core Torque Mode Setup: P2 Parameters
To get this running on the 300N series, you need to configure the P2 group. These parameters dictate how the drive calculates the torque limit and how aggressively it responds to changes. Here is the exact setup we use on the test bench.
P2-09: Torque Upper Limit Source
Range: 0-7 | Default: 0
Determines where the max torque limit comes from. Set to 0 to use the digital setting in P2-10, or 5 to pull the limit via Modbus RTU communication from your PLC.
P2-10: Digital Max Torque Setting
Range: 0.0%~200.0% | Default: 150.0%
The hard ceiling for your torque output. We usually set this to 120% for winding applications to prevent web breaks, and 150% for hoisting.
P2-15: Torque Adjustment Ratio Gain
Range: 0~60000 | Default: 2000
The proportional gain for the torque loop. If your torque response is sluggish, bump this up. If it oscillates, back it down.
P2-16: Torque Adjustment Integral Gain
Range: 0~60000 | Default: 1300
The integral gain. This eliminates steady-state error. Increase it to make the torque catch up to the target faster, but watch for overshoot.
Monitoring and Fine-Tuning the Loop
Once the basic setup is done, you need to watch the motor behave. The 300N provides real-time monitoring parameters. You will want to track U0-35 (Target Torque) on your keypad or via your SCADA system. This tells you exactly what the drive is trying to output versus what it’s actually doing.
Tuning on the Floor
When I’m standing at the test bench with a 55kW drive hooked to a dynamometer, I start with P2-15 at 2000 and P2-16 at 1300. I command a 50% torque target and watch U0-35. If the actual torque takes too long to reach 50%, I increase P2-16 in steps of 200. If the motor starts vibrating or the torque spikes past 55%, I drop P2-15 by 200. It’s a balancing act between speed of response and stability. For Modbus communication setups, ensure your polling rate is fast enough so the PLC doesn’t miss the torque limit updates.
Wiring and Hardware Considerations
Torque control relies heavily on accurate current feedback. The internal current sensors on the power stage must be perfectly calibrated. At SHZK, every power board undergoes a strict calibration routine before assembly.
Analog Reference Wiring
If you are using an analog signal (0-10V or 4-20mA) for the torque reference, keep your shielded cables away from the motor power wires. Noise on the analog input will cause the drive to constantly adjust the torque, leading to mechanical wear. Use AI1 or AI2 for the reference, and ensure the jumper on the control board is set correctly for voltage or current input.
Troubleshooting Common Torque Issues
Motor stalls under load: Your P2-10 torque limit is too low, or the motor is undersized for the application. Check U0-35 to see if the target torque is hitting the P2-10 limit and flattening out.
Torque oscillation/hunting: Your P2-15 and P2-16 gains are too high. The drive is overcorrecting. Drop the proportional gain (P2-15) first.
Overvoltage faults during deceleration: In torque mode, if the load is driving the motor, it acts as a generator. Ensure your braking resistor is wired correctly and the brake transistor is functioning.
Need help selecting the right VFD? Contact our engineering team at mail@shzkvfd.com or WhatsApp +86 13757750205 for free application consultation.