What is a variable speed drive?
KineSys variable-speed drives (DVA) are characterized by the perfect symbiosis of hydraulics and electronics. Thanks to the integrated control unit, the motor can be switched on and controlled as required. This results in the greatest potential for energy savings, since only the required amount of energy is made available. Energy savings of up to 70% depending on the machine cycle can be achieved. Thanks to the state-optimized adaptation of the KineSys solution, the power loss is reduced to a minimum and the complexity on the hydraulic side is reduced drastically.
Control
Closed loop control
"A control loop is the fundamental building block of industrial control systems. It consists of all the physical components and control functions necessary to automatically adjust the value of a measured process variable to equal the value of a desired set-point."[1]
Speed control
If the system of the general control loop is transferred to the control types occurring in hydraulics, the following block diagram for speed control is obtained.
The difference between setpoint and actual speed is transferred to the frequency converter. The inverter then controls the motor so that the control difference (in our example, the speed deviation) is as close to zero as possible.
Pressure control
This analogy can also be applied to pressure control. The difference between setpoint and actual value determines the control of the motor. The physical pressure is measured by a sensor within the fluid and serves as a reference value for the controller.
Accumulator-charging-operation
Accumulator charging operation is a special application of pressure control. The underlying controller structure is identical to the above figure.
If the desired set pressure is reached and there is no hydraulic power consumption, the drive runs at minimum speed to ensure continuous lubrication of the hydraulic pump. After an adjustable time (Δtimehysteresis), the drive is switched off completely. If the currently measured pressure value falls below the difference of pressuresetpoint and Δpressurehysteresis, the drive switches on again and automatically goes into pressure control. On the basis of this operating mode, the greatest possible energy savings can be realized.
Parameterization
What is a parameterization?
"Parametrization, also spelled parameterization, parametrisation or parameterisation, is the process of defining or choosing parameters."[2]
This is equivalent to the parameterization progress of our drive controllers. Via the different parameters, functional values are getting defined e.g.:
- Minimum and maximum speeds
- Control modes
- Processing of digital and analog input and output signals
- Bus system interfaces
- etc.
HFI-MM Antriebsregler
Standard parameterization
Means?
Based on our many years of experience with regard to a wide variety of applications, we have defined standards that fully cover most use cases. Adaptations to your system are of course taken into account in each of our delivered products. In the following the already above described 3 main control types and their standard parameterizations are shown:
Speed control
The most important parameters that are present within the delivery state of a drive controller with speed control are listed below.
| Parameter number | Description | Value | Unit |
|---|---|---|---|
| 1.020 | Minimum frequency | 25 | Hz |
| 1.021 | Maximum frequency | 100 | Hz |
| 1.050 | Deceleration time 1 | 0,1 | s |
| 1.051 | Run up time 1 | 0,1 | s |
| 1.100 | Operating mode | Frequency setting mode | - |
| 1.130 | Target value source | Analogue input 2 (0-10 V) | - |
| 1.131 | Enable software | Digital input 1 (24 V) | - |
| 1.150 | Rotation direction | Forwards only | - |
| 1.180 | Acknowledge function | Digital input 4 (24 V) | - |
- Speed setpoint by customer on analog input 2
- Analog input 1 for pressure sensor (no effect on speed control)
- Enable drive via digital input 1
- Acknowledgement of pending errors via digital input 4
Pressure control
The most important parameters that are present within the delivery state of a drive controller with pressure control are listed below.
| Parameter number | Description | Value | Unit |
|---|---|---|---|
| 1.020 | Minimum frequency | 25 | Hz |
| 1.021 | Maximum frequency | 100 | Hz |
| 1.050 | Deceleration time 1 | 0,1 | s |
| 1.051 | Run up time 1 | 0,1 | s |
| 1.100 | Operating mode | PID process controller | - |
| 1.130 | Target value source | Analogue input 2 (0-10 V) | - |
| 1.131 | Enable software | Digital input 1 (24 V) | - |
| 1.150 | Rotation direction | Forwards only | - |
| 1.180 | Acknowledge function | Digital input 4 (24 V) | - |
| 3.050 | PID-P amplification factor | 1 | 1 |
| 3.051 | PID-I amplification factor | 1 | 1/s |
- PID process controller for pressure control
- Setpoint input by customer via analog input 2
- Enabling of the drive via digital input 1
- Acknowledgement of pending errors via digital input 4
- Presetting of the P and I components of the controller
Accumulator-charging-operation
The following are the most important parameters that are present within the delivery state of a drive controller with accumulator charging operation.
| Parameter number | Description | Value | Unit |
|---|---|---|---|
| 1.020 | Minimum frequency | 25 | Hz |
| 1.021 | Maximum frequency | 100 | Hz |
| 1.050 | Deceleration time 1 | 0,1 | s |
| 1.051 | Run up time 1 | 0,1 | s |
| 1.100 | Operating mode | PID process controller | - |
| 1.130 | Target value source | Analogue input 2 (0-10 V) | - |
| 1.131 | Enable software | Digital input 1 (24 V) | - |
| 1.150 | Rotation direction | Forwards only | - |
| 1.180 | Acknowledge function | Digital input 4 (24 V) | - |
| 3.050 | PID-P amplification factor | 1 | 1 |
| 3.051 | PID-I amplification factor | 1 | 1/s |
- Presetting of the P and I components of the controller
- Setpoint input by customer via analog input 2
- Enabling of the drive via digital input 1
- Acknowledgement of pending errors via digital input 4
- PID process controller for pressure control
| Parameter number | Description | Value | Unit |
|---|---|---|---|
| 3.060 | PID actual value | Analogue input 1 (0-10 V) | - |
| 3.070 | PID stand-by time | 0,01 | s |
| 3.071 | PID stand-by hysteresis | 10 | % |
- Stand-by time = switch-off time after reaching the set pressure + minimum speed
- Stand-by hysteresis = switch-on and switch-off thresholds related to the set pressure
- Pressure value as actual value of the PID controller on analog input 1 (already wired at the factory).
Option fieldbus system
If the drive controller is ordered from KineSys with the "Fieldbus" option, the following process data is made available for reading and writing as standard. Further information can be found within the documentation of the respective bus system.
| Parameter number | Description | Value | Unit |
|---|---|---|---|
| Not parameterizable | Process data out 1 | Status word | - |
| Not parameterizable | Process data out 2 | Actual frequency | Hz |
| 6.080 | Process data out 3 | Motor voltage | V |
| 6.081 | Process data out 4 | Motor current | A |
| 6.082 | Process data out 5 | Grid voltage | V |
| 6.083 | Process data out 6 | Target frequency value | Hz |
| 6.084 | Process data out 7 | Digital inputs with bit coding | - |
| 6.085 | Process data out 8 | Analogue input 1 | V |
| 6.086 | Process data out 9 | Error word 1 | - |
| 6.087 | Process data out 10 | Error word 2 | - |
| Not parameterizable | Process data in 1 | Control word | - |
| Not parameterizable | Process data in 2 | Target value | % |
| 6.110 | Process data in 3 | Digital output - relay | - |
| 6.111 | Process data in 4 | Analogue output 1 | V |
| 6.112 | Process data in 5 | Customer-specific input value 1 | - |
| 6.113 | Process data in 6 | Customer-specific input value 2 | - |
Wiring diagram
The two wiring diagrams for motor-mounted frequency inverters from KineSys with and without fieldbus interface are shown below.
The control of a valve via digital output and optocoupler is an option and does not represent the standard delivery conditions.
