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Real Applications

7.6An Exercise Machine Application

A running machine uses a variable speed drive to control the running belt speed from a slow walk to a fast run.

7.6.1Advantages

·Excellent low speed torque ensures smooth operation even at low belt speeds with a heavy step.

·Wide speed range makes good use of motor.

·External class B filter meets domestic and light industrial requirements.

·Automatic motor protection due to continuous current monitoring.

7.6.2System Specifications

Motor

2.2 kW 230 V 3-phase induction motor

Control

Microprocessor control system with display, keypad etc.

System

 

Drive

MICROMASTER MM420 2.2 kW 230 V

Drive Control

Analog and digital input controls, fault indication via output

Interface

relays

7.6.3Application Details

A 2.2 kW motor drives a pulley and flywheel system via a toothed belt. The motor is controlled by a 2.2 kW inverter with an external input filter to reduce EMI. The inverter is connected to the main controller via an analog frequency control and digital inputs. The digital inputs are used to run, stop and reset invert faults.

The I2t function will help protect the motor in this application. Continuous high load operation is unlikely, but the inverter will trip if the motor is in danger of overheating. This is acceptable in this application. The fault relay is used to alert the user of this condition.

Display and Panel

Controller

Motor

Inverter etc.

Running Belt

Drive Belt

Figure 7-6 Exercise Machine

MICROMASTER Applications Handbook

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