Peak Power Rating; Selecting The Correct Gen4 Model; Current And Power Ratings Considerations; Power Output Restrictions At Motor And Drive Operating Temperature Limits - Sevcon Gen4 Applications Reference Manual

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Peak power rating

The peak power rating required for the application is actually determined by the peak torque
required, as this determines the motor current required. Motor manufacturers will provide S1, S2
or S3 duty cycle ratings for the motors.

Selecting the correct Gen4 model

Matching motor and controller ratings is not an exact exercise and therefore you may need to
perform iterative calculations. The main considerations when choosing an appropriate Gen4
controller are described below.

Current and power ratings considerations

Consider the following when choosing the appropriate Gen4 controller:
Ensure the controller chosen matches or exceeds the peak current and average current
requirements of the motor(s) in the application.
Ensure the application can dissipate the waste heat generated by the controller. If the
controller gets too hot it reduces its output, limiting vehicle performance.
Power output restrictions at motor and drive operating
temperature limits
A controller protects itself by reducing the current and hence torque available when its
temperature limit is reached (Figure 12).
120
100
80
60
40
20
0
80
82
Figure 12 Current allowed vs. controller base temperature
5-4
Gen4 Cutback Curve
84
86
88
Base Temperature (°C)
90
92
94
96
98
100

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