Parker: BLH & BLHX Series Brushless Servo Systems (BLH-XX)
BLH/BLHX
Series motor/drive packages offer a low cost solution in a wide range of
brushless servo applications. The package includes a pre-cabled motor and drive
with integral power supply for direct operation from an isolating transformer.
The present range includes a choice of four motors, analog command servos and
digital positioning servos. With peak torques between 56 oz-in (0.4 Nm) and
1840 oz-in (13 Nm) and speeds of up to 11,000 rpm these packages offer
incredibly high performance in a small package size.
All motors
are two-phase brushless designs using rare earth magnets. Commutation is
derived from an absolute encoder while position feedback is derived from an
incremental encoder. Both encoders are robust metal disk encoders mounted
directly to the motor shaft. The commutation encoder provides 16 states per
electrical cycle and superior torque ripple to trapezoidal DC brushless systems
and does not incur the cost penalty of conventional sine wave drives. The
incremental encoder has a resolution of 500 lines/rev or1,000 lines/rev
depending on motor size. A tachometer is not required because velocity feedback
can be derived from the incremental encoder.
The drive
circuit is based on a proven recirculating PWM design. Recirculating technology
reduces chopping losses in the drive and motor hence increasing system
efficiency. Surface mount components and power plate technology increase
reliability through better thermal management and consistent manufacture. The
built-in power supply operates from a single AC input voltage and employs a
switching regulator to generate integral power supplies. Protection circuits
guard against short circuit of the motor phases, overheating of the drive and
supply faults. An integral braking resistor dissipates regenerated energy.
Isolating AC
power is the generally accepted practice when responding to emergency stop
conditions, this removes power from the motor and renders the system safe. An auxiliary
24VDC input is provided to maintain the internal logic supplies while the AC
power has been removed. This provides the benefit of maintaining power to the
motor encoder so that the controller knows where the motor is, making system recovery
easier, and the additional benefit that communication can be maintained with
the controller to determine status. The auxiliary 24VDC input is available if
this capability is required, but is not necessary for general operation.
BLH Series
drives accept an analog command signal for torque or velocity control
applications or for use with a multi-axis servo controller. The BLHX Series drives
combine a BLH drive with a positioning card in one package for single-axis positioning
applications.
BLH and
BLHX Common Features
• Two versions
BLH – Analog
command servo
BLHX –
Digital positioning servo
• Supplied as complete, ready wired motor/drive
packages
• Drive operates in torque or velocity
amplifier modes
• Simplified drive set-up and adjustment
• LED diagnostics
• Drive outputs for motor are short-circuit
protected
• Direct operation from isolating transformer
• Maintenance free brushless motors
• Torques up to 1,840 oz-in (13 Nm)
• Speeds up to 11,000 rpm
• Motor has built-in incremental encoder for
position
feedback.