Analogue Inputs – SOLO UNO

Analogue Inputs and +5V External Supply

This is the Analogue commanding port of SOLO, through these inputs/outputs, you can control the Speed or Torque of your motors by sending analogic commands using ​PWM pulses with any frequency above 5kHz or ​sending direct analogue voltages rated from 0V to 5V​, you can also use them to limit the current fed into your Motor in a completely Analogue Mode ( ​see the Minimum Required Wirings Section​)

 

This part is composed of 5 pins as can be seen below:

Analogue Inputs - SOLO UNO 1

1. “GND” PIN 

This is the Ground or in another word the 0V reference of SOLO, so if you want to send an analogue commands to SOLO, you need to make sure the Ground of the commanding unit ( Arduino, Raspberry Pi , … ) is shared and connected with SOLO at this point.

2. “+5V” PIN

This is a 5V/1A output to supply external peripherals or controllers, remember that this output is fused, and if you drain more than 1A, the fuse will be blown ( internally ) and this output will become dysfunctional for safety reasons.

3. “DIR” PIN

This is the Direction control pin which is a digital pin, accepting voltage levels of 0V or 3.3V, so by giving each of these values, the connected Motor to SOLO, will either rotate in C.W. direction or C.C.W. direction.

4. “P/F” PIN 

This is a pin with three main different functionalities depending on the control Mode and the type of the motor you select as below:

4.1. In Open Loop mode of 3 phase motors : It will act as increasing or decreasing the injected power into the Motor, so by applying 0V of analogue voltage or 0% duty cycle of PWM, there will be no power injected inside the Motor, and at 5V or 100% duty cycle of PWM, it will apply the maximum deliverable power into the Motor.

4.2. In Closed-Loop mode of DC, BLDC and PMSM motors: It will act as the current Limit, so if the voltage applied to this pin is 5V, it will stop the current floating to the motor ( current Limit at zero), and if this pin is left open it will allow up to 32A floating into your Motor, so any value between these will define the value of current limit. You can calculate the current limit value based on following formulas:

In case of using PWM:

The current Limit value = ((100 – duty cycle precentage of PWM at P/F input)/100) * 32.0

In case of using Analogue Voltages:

The current Limit value = ((5.0 – the voltage at P/F input)/5.0) * 32.0

4.3. In Closed-loop mode of AC Induction Motors:
it will act as the reference for magnetizing current reference known as ​“Id” which is in charge of generation of stator flux. The maximum amount of current that can be injected into the motor using this pin is 10Amps. So in order to calculate the amount of magnetizing current you can use the following formulas:

In case of using PWM:

The Magnetizing current value = ((100 – duty cycle of PWM at P/F input)/100) * 10.0

In case of using Analogue Voltages:

The Magnetizing current value = ((5.0 – the voltage at P/F input)/5.0) * 10.0 

5 “S/T” PIN in Closed_loop Mode 

This is the input for controlling Speed or Torque of the Motor connected to SOLO, you can select this mode using the ​Piano switch mentioned in section 6, the analog voltage or the duty cycle of PWM pulse applied in either of the conditions will be treated as a desired reference of the user based on following explanations:

5.1. In Torque mode: if you apply an analog 5V or in case of using PWM inputs, a 100% duty cycle to this pin, without having a current limit, SOLO will try to inject 32A of current inside your motor, given this, the amount of Torque for motors generally can be calculated:
Applied Motor Torque = Current acting in torque generation * Motor Torque Constant
The “Current acting in torque generation” for DC motors is shown with “IM” and the same for 3 phase motors (BLDC , PMSM or ACIM) is shown by “Iq” or namely the “Quadrature current”. So the amount of active current in torque generation injected to your motor based on the amount of voltage or duty cycle you apply to S/T pin can be calculated as:

In case of using PWM:
The torque generation Current = ((100 – duty cycle of PWM at S/T input)/100) * 32.0

In case of using Analogue Voltages:
The torque generation Current = ((5.0 – the voltage at S/T input)/5.0) * 32.0

5.2. In Speed mode: if you apply an analog 0V or in case of using PWM inputs, a 0% duty cycle to this pin , it will keep your motor’s speed at 0 RPM, and at the same time by applying 100% duty cycle or 5V analogue input, SOLO will force your motor to go to the maximum speed based on the Motors type as below, of course your motor should be able to reach to that speed, otherwise it will stay at its nominal speed even if you keep increasing the duty cycle.

Analogue Inputs - SOLO UNO 2

For instance, if we take Normal Brushless motors as an example, and in case of applying analogue voltages, the speed of the motor can be found based on the following formula:
The Normal BLDC motor speed [RPM] = ((5.0 – the voltage at S/T input)/5.0) * 12000

s

To have accurate 3 phase motors speed measurements by SOLO, if needed, you need to set the number of Poles of you motor at their exact value using one of the methods in “​Digital Commanding and Control​” section, since the default value for number of poles in SOLO is set at 8. If you don’t change this value SOLO will still function but you might need to tune this value if you need the best performance in speed tracking and estimation in sensorless mode.

6. “S/T” and “P/F” PINs in Open-loop Mode

In Open-loop Mode to control the speed of 3 phase Motors, you need to set both “S/T” and “P/F” voltage values to apply the desire speed and power respectively, and for each of them you can find
the explanation below:

the speed of the motors in ​RPM can be derived from the following formulas based on the motor type selected on Piano Switch, (​Section 6)​:
Number of Motor Pole Pairs = Number of Motor Poles / 2

6.1. In case of using Analogue Voltages on “S/T”:
– Normal Brushless Motor​ = (voltage applied at “S/T”)/(5.0* Number of Pole pairs)*12000
– Ultrafast Brushless Motor​ = (voltage applied at “S/T”)/(5.0* Number of Pole pairs)*30000
– AC induction Motors​ = (voltage applied at “S/T”)/(5.0* Number of Pole pairs)*12000

6.2. In case of using PWM inputs on “S/T”:
– Normal Brushless Motor ​= (PWM duty-cycle Percentage at “S/T”)/(100%* Number of Pole pairs)*12000
– Ultrafast Brushless Motor = (PWM duty-cycle Percentage at “S/T”)/(100%* Number of Pole pairs)*30000
– AC induction Motors = (PWM duty-cycle Percentage at “S/T”)/(100%* Number of Pole pairs)*12000

7. Three phase Motors “Power” Notation in Open-loop Mode 

The “P/F” input in open loop mode of 3 phase motors acts as the output voltage adjuster, so by going all the way up from 0V of Analogue voltage or 0% duty-cycle of PWM inputs at this pin to +5V or 100%, you will increase the peak 3 phase voltage resulted by SVPWM modulation on SOLO to the motor ​linearly from 0V to Vbus/sqrt(3) or equivalently to Vbus*0.577 at maximum, Vbus here refers to the DC supply input voltage ( or battery voltage )​, the action of increasing the output voltage peak, will result in higher consumption by the motor depending on their phase resistance and finally having more power for their rotation.