Moog DS2100 User Manual download pdf (Page 222)

DS2100 User's Manual SECTION 5: DS2100 FUNCTIONAL OVERVIEW

PAGE 5-74

5.13 Self Protection

5.13.1 Power Amplifier Thermal Protection Mechanism

The power amplifier is protected by using a scheme called Thermal-Foldback. The DS2100 is rated to operate at an

ambient temperature of up to 40°C.

 The Foldback scheme is designed to ensure a very conservative temperature margin is maintained between

power device manufacturer's rated maximum temperatures (semiconductor junction temperature) and the actual

semiconductor junction temperature.

 The Running Thermal Limit applies when the speed of the motor is greater than approximately 50RPM. The

Stall Thermal Limit applies for motor shaft speeds of less than approximately 50RPM. The Stall Limit will

become less than the peak current capability of the amplifier only at elevated ambient temperatures and high

continuous operating loads.

5.13.2 Motor Thermal Protection Mechanism

 The DS2100 can measure the temperature of the motor by means of a Negative Temperature Coefficient

thermistor (NTC) or a Positive Temperature Coefficient thermistor (PTC) buried within the motor windings.

With the motor NTC, temperature is measurable between approximately 25°C and 175°C.

The PTC acts as a thermal switch so linear temperature measurement of the motor is not possible. When this

device changes from a low impedance state to a high impedance state, the software will detect and report a

fault.

 Software calculates the motor thermal limit based upon the motor windings temperature. The motor protection

scheme is intended to ensure that the temperature of the motor core will not exceed 155°C.

5.13.3 Cabling and Interconnect Protection Scheme

Each DS2100 model has a continuous current rating. The DS2100 operates an algorithm that limits the overall RMS

level of motor phase current appropriately, over a time window. This is intended to protect the connectors and

internal circuitry, which would otherwise be thermally over-stressed.

The DS2100 measures the motor phase currents at a high frequency. It calculates the remaining amount of current

for the next period to ensure that the overall RMS current rating of the drive is not exceeded.

5.13.4 Regeneration Resistor Protection Scheme

The DS2100 can be equipped, depending on the model size, with an internal or external regeneration resistor. The

algorithm controlling the duty cycle of the resistor ensures that the power dissipated by the resistor is maintained at

the resistor rating provided by the user.

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Moog DS2100 User Manual Page 222