Technogym Run XT - Tread-Belt Motor Drive System

RUN XT: Service & Maintenance Manual - rev. 2.0
Page 3.4
3.2. TREAD-BELT MOTOR DRIVE
The tread belt is actuated by the motor through a linkage consisting of the motor pulley, the driving
roller and the belt which connects them. In this way, a given belt motor speed corresponds to a
predetermined linear tread belt speed. The belt motor is controlled by the inverter which generates a
variable-frequency sine wave signal: variations in frequency cause the motor speed and hence the
tread belt speed to vary.
The machine controls the speed of the belt motor by means of the CPU board and the inverter
interface board, as shown in the figure below:
The speed control utilizes 3 signals:
• Start signal
This is the signal generated by the CPU to enable starting of the motor (pin 7-3 of connector
CN1 on the CPU board). When the tread belt is stopped this signal is at logic level low (0 Vdc),
whereas immediately after the “Start” button on the display is pressed it goes high (4.5 Vdc).
The signal enters the inverter interface board (pin 8-3 of connector CN2 on the inverter interface
board), is processed and sent to the inverter (pin 2-1 of connector CN1 on the inverter interface
board). In the belt-stopped condition it is -24.7 Vdc, while immediately after pressing the “Start”
button on the display it is -2.7 Vdc.
• Speed reference signal
This is the signal generated by the CPU (pins 6-3 of connector CN1) to control the motor speed.
It is a PWM signal, that is to say a fixed frequency square wave with a variable duty cycle. The
logic of this control has the duty cycle decreasing with increasing speed. The measurement of its
DC component with a multimeter shows a value that decreases with increasing speed, from a
maximum of approximately 5 Vdc down to a few hundred mVdc.
This signal enters the inverter interface board (pins 10-3 of connector CN2), is converted into a
variable analogue signal between 0 and 10 Vdc and sent to the inverter (pins 5-6 of connector
CPU board
Inverter
interface board
Inverter
Alarm
Alarm
Start
StartPWM
Vref