The servo amplifier is based on a cascade control system, consisting of a PID controller of speed/position and PI current controller. Control system and protection system are software implemented on the basis of microcontroller.
The servo amplifier has a separate power circuit for converter and its power section. The servo amplifier can be powered by AC or DC. The power section can be powered by three-phase or single-phase current, and DC. Single-phase power supply is recommended for use for the electric motor rotor current up to 10A. When necessary to coordinate the supply voltage to the voltage of the electric motor, an additional transformer is used.
The power section of the servo converter is based on the H-bridge on IGBT or MOSFET transistors. The frequency of the Pulse Width Modulation (PWM) of the amplifier is 8 kHz. To avoid any excessive currents when you switch on the network, servo amplifier contains scheme of smooth charging of filtering capacitors. To avoid overvoltage in the DC, the link servo amplifier converter has a chopper with brake resistor.
Connecting the Electric motor.
The servo amplifier is designed to work with one electric motor. The servo amplifier allows you to connect most types of electric motors without additional. However, using electric motors with low rotor inductance, such as motors with disc rotor, the series extra inductance must be connected.
Secondary power supply.
The servo converter contains secondary power supply that are derived on connectors and available for use as follows,
• +10 V, -10 V – to power an external analog adjuster (of potentiometer);
• +5 V, +15 V, +24 V – to power the feedback encoder, digital inputs, an auxiliary fan. All secondary power supplies have a galvanic isolation from the power unit and the power supply voltage of the servo converter.
Analog inputs, namely the input of the reference and the input of the feedback (of Tachogenerators), have a galvanic isolation from power unit and power supply voltage of servo converter, but have a common ground with the secondary power supply. The servo converter contains elements of sensitivity setting of feedback input that allows you to apply tachogenerators with different output voltage.
Under digital inputs, it means «Enable», the inputs of discrete reference and the input of the encoder signal. Each digital input has galvanic isolation of all circles of servo amplifier and other digital inputs. Each digital input has its own input voltage settings (sensitivity) and protected against turning on the reverse polarity. This allows a flexible configuration of the servo converter.
The servo amplifier has two digital outputs - output "Ready" and the output of the control of the brake coupling. Both digital outputs are relay, normally open, not linked.
Brake coupling control.
The servo converter allows you to control brake coupling of electric motor. Switching on the coupling happens after giving a signal to «Enable» on the readiness of the servo converters and the turning off occurs after its removal and stop of the electric motor. After triggering the protections, switching off the coupling occurs instantaneously.
The servo controllers design.
The servo converters is made in a single design as a unit and proposed to be installed in electrical cabinets. The servo amplifier orientation is vertical, with power terminal block into the down. The necessary parts to configure the regulators and indicators located on the front board and are accessible for user.
The servo converter contains the following connecting elements, configuration, and display
Jumper of analog input filter connection (closed condition - filter connected)
Jumper switch of the analog Tachogenerator input sensitivity
Jumpers of the discrete reference input signals levels, closed condition - 5 V, open- condition – 24 V
Converter condition indicators - "Ready" on the left and "work" on the right
Balancing potentiometer of the analog input of the speed controller
Potentiometer of smooth sensitivity tuning of the analog Tachogenerator input
Potentiometers of settings PID controller speed / position and PI current regulator
The serial interface (UART) connector
Terminal block of the armature connection of electric motor and power supply
Connector of the power supply
Connector of the feedback
Jumpers of the input signals levels of feedback A/B (encoder), closed condition - 5 V, opened – 24 V
Jumpers of the input signal levels of «Enable», closed condition – 5 V, opened – 24 V
Programming connector (PDI)
Indicator of armature current
Indicator of faults triggering
connector of the service display
Switch of the ratio of the pulse reference and discreteness of encoder (coefficient 1:1-1:16)
Connector to connect an external fan (24 V, 400mA)