CA3039987A1

CA3039987A1 - Automatic start and speed command circuit

Info

Publication number: CA3039987A1
Application number: CA3039987A
Authority: CA
Inventors: Anthony Mastromattei; Jordan Luigi Mastromattei; Robert Aldo Mastromattei
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-04-10
Filing date: 2019-04-10
Publication date: 2020-10-10

Abstract

Automatic start and speed command circuit for supplying an analog start acceleration and preset signal to an AC electric motor controlled by a variable frequency motor and or brushed/brushless DC motor controller or any electric motor speed control or drive which uses an analog speed command signal input for supplying a variable analog speed command to the controller for setting an operational motor speed. This includes manually speed setting device such as potentiometer.
Automatic start and speed command circuit will provide a cycle start after which will increase the command to said electric analog drive to accelerate the motor for an allotted time to allow the controller and motor to achieve the commanded speed at the motor, the speed command is incrementally increased till maximum speed or set speed is achieved.
A adjustable time base is included for each increase of command speed to allow for tuning the start up performance of the motor. An isolated power source is included which provides power to the circuit and is isolated from the command signal on the drive or controller as not to interfere with input command on the drive and/or controller.

Description

AUTOMATIC START AND SPEED COMMAND CIRCUIT
BACKGROUND
This invention relates to a start and speed command circuit and, more particularly to a speed command control that provides a continuous increase in acceleration to a set point for starting and further set point speed command to a final set point speed after the starting of an electrical motor drive control.
DESCRIPTION OF PRIOR ART
Start and speed command developments are required in many applications to determine start and speed command levels to insure proper operation of equipment. Traditionally, speed command has been accomplished by hall affect and manual settings that rely upon manual input changes of the device in response to start and speed command changes of the electrical motor drive. These electrical motor controlling devices require manual operation and vary from their designed commanded operational characteristics. One object of the present invention is to provide an automatic reliable electrical motor drive automatic start and speed command signal for starting and running speed.
SUMMARY OF THE INVENTION
This invention includes a start and speed command circuit that provides a start control system and speed stepped approach to starting and speed setting for the drive. These controls are utilized by devices to increase the efficiency of the motors and hence the systems and devices that use them.
Both DC and AC drive systems are used to provide efficient and proper operation during normal conditions, and maintain proper and safe use. The frequency of or, expressed alternatively, the interval between successive increase speed commands is selected to prevent stalling and excessive current draw under heavy usage conditions. For example, Variable Frequency Drives permit the user to optimize the control speeds based on a particular AC motor characteristic and usage conditions.

BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of this invention mentioned above will become more apparent as the invention becomes better understood by the detailed that follows, when considered in connection with the submitted drawings.
FIGURE 1 is a schematic diagram of the auto start and speed command circuit.
FIGURE 2 is an overview of the auto start and speed command circuit output to the electric motor drive.
FIGURE 3 is a timing chart of the output signals produced by the auto start and speed command circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
This invention includes a start and speed command circuit with two speed transition points one transition point provides an start to a preset speed set point transition command and the second set point is the transition to maximum preset speed. Externally started speed command. Fig 3 is the schematic diagram of the embodiment of this invention. Connected to two Dual Solid State Relay (SSR) comprises two independent, optically coupled, bidirectional MOSFET switches. The first having a normally closed switch and coupled to it a node consisting of a capacitor and resistive element and at the same node the final output command to the drive. The command follows the charging curve of the capacitor till it reaches the maximum value which is the first speed command for the first setting. During which Fig 1 (10) a 555 timer having it's trigger inputs coupled to the node of the voltage divider resistive and capacitance timing sensing node of the said 555 timer outputting the time base of switching the command relays relay logic state when energized opens the first bidirectional MOSFET switch and closes the switch of the second bidirectional MOSFET switch and having a resister element electrically connected to the Zener diode which is electrically connected to the node of the final output and providing a command voltage on the said node in accordance to the voltage of the Zener reversed bias voltage.

2. The circuit starts when the input is applied to Fig. 1 (1) as a start signal with a switch closure closes the switch of the first bidirectional MOSFET switch Fig. 1 (10) and power is provided to Fig 1 (7) of the Fig 1 (20) 555 timer and at this time the capacitor is discharged therefore there is 0 volts at the Fig 1 (8) Threshold which is the positive input to the second internal comparator in the 555 timer semiconductor Fig 1 (10) and since the V+ input is lower than the negative side of the internal comparator input the output stays low and does not trigger the input of the internal flip flop.

3. When we switch the Trigger input Fig 1 (7) of the 555 timer and the input is pulled low this will provide V- 0 volts to the negative input of the Fig 1 (10) 555 timer's said first comparator and the V+ is higher than the negative input on the comparator which turns the output high which is tied to the internal flip flop set input and the flip flop is triggered and the output of Fig 1 555 timer (10) 12 output is driven high by the flip flop and said output provides a positive input to both and Fig 1 (30) and Fig 1 (40) Dual Solid State Relays, optically coupled, bidirectional MOSFET switch the first and second opto-isolated relays.

4. The Dual Solid State Relay, optically coupled, bidirectional MOSFET
switches. This normally open switch, from the Fig 1 (30) dual OptoMOS
Relay provides both switches the first is normally open and the second is normally closed and configured as a single pole double throw configuration. When the Fig 1 (30) and Fig 1 (40) inputs are in the off condition the first optically coupled, bidirectional MOSFET switch is normally closed and the external command reference is connected to the switch which feeds the resistive capacitor elements and causes the capacitor Fig 1 (25) to charge while the output voltage increases which causes a ramping effect in respect to the charging curve of said capacitor Fig 1 (25) and the signal increases during the timing of the input to the 555 timer Fig 1 (20) and when the output from the timer is turned on the optically coupled, bidirectional MOSFET switch Fig 1 (30) and Fig 1 (40) which are coupled on the node receives a positive input and the output of the first bidirectional MOSFET switch opens and the output of switch one is off and the second bidirectional MOSFET switch closes and the output of the second bidirectional MOSFET switch provides a voltage to the output coupled to node at Fig 1 (23)resistive element and Fig 1 (26) Zener diode.

5. The Fig 1 (26) Zener diode is driven in reverse bias till the reverse output of the diode is reached and provides the maximum output value for the circuit.

6. The fifth bidirectional MOSFET relay signal Fig 1 (30) and sixth Fig 1 (40) bidirectional MOSFET relay signal is turned off by the external process;
the internal switches open on the first relay which removes the start signal from the Fig 1 (20) 555 timer trigger Fig 1 (20) 7 and the sixth bidirectional MOSFET relay closes when de-energized and makes the connection between on the node Fig 1 (20) 7 which has a value of 0 volts as the internal discharge transistor of is on Fig 1 (20) and the transistor output is at 0 volts the Discharge signal on the Fig 1 (20) 555 timer and Fig 1 (20) 8 the threshold pin which is tied to the second comparator V+ Fig 1 (20) 555 timer now is low which is lower than the V- input of the second comparator Fig 1 (20) 555 timer and the output is turned off to the Fig 1 (20) 555 timer flip flop and the circuit resets.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an automatic start and speed command apparatus for an electric motor drive system;
(a ) An automatic start and speed command apparatus to provide automatic start and speed command with a generated acceleration command reaching a predetermined set point and after a predetermined time provide a second command for the second set point whereas acting as a final speed for the application based on the drive motor rating and the requirement of the application.
(b) a drive means a electric motor control which maybe a brushed or brushless DC motor, variable frequency drive, or a servo drive having an analog input for control.
(c) starting means to energize the motor by providing a start signal and a speed command in the case of brushless DC whereas the signal is provided by a manually operated hall effect device or an adjustable resistor.
(d) a speed command signal means a signal to a drive which by its magnitude relative to the input range of the drive will produce a speed in relation to the command.
(e) an electrical speed command control to energize the motor command signal and having a predetermined speed and incremental steps during the acceleration of the drive motor for achieving maximum or final set speed.
(f) means to run the speed command control only when the motor is stopped and required to start.
(g) means to automatically provide a start command and incremental increase in acceleration after the drive has been energized.

2. In the drive system of claim 1 wherein means to delay the running speed of the drive is an electrical speed control after energizing of the drive at the beginning of each start cycle, switch means are actuated to energize the electrical speed command control.

3. An automatic start and speed command apparatus of claim 1 comprising: Three Dual Solid State Relays comprises two independent, optically coupled, bidirectional MOSFET switches for changing states of the signals as described on Fig 3 and a 555 timer to provide a preset time delay for two of said switches and connected to a node comprising of resistive capacitive series network and a node of series connected resistive element and capacitive element to provide automatic generation of a start and acceleration command signal connected to an adjustable 555 timer to provide timing for the initiation of the run speed for the drive and motor connected to the circuit and in operative association with an electric motor controller with an analog input with a reference for accepting speed commands relative to the drives internal reference voltage.

4. The automatic start and speed command apparatus of claim 2 where the external start connected to the input of the first dual solid state relay comprises two independent, optically coupled, bidirectional MOSFET switches with the first contact having a normally closed contact and electrically connected to a node consisting of a capacitor and is coupled to both the trigger and threshold inputs of said 555 timer and the second normally closed contact electrically connected to the node and the said discharge connection varying the voltage at the node in synchronism with a change in the logic state output signals of said 555 timer.

5. The automatic start and speed command apparatus of claim 2 wherein the first of two Dual Solid State Relays comprises two independent, optically coupled, bidirectional MOSFET switches for initiating an automatic generation of a ramping command signal connected to an adjustable resistive capacitive network to provide said optically coupled, bidirectional MOSFET
switch, contact closure allowing signal to start and accelerate and a 555 timer to provide timing for the initiation of a second set point setting for the run speed and adjustable resistive element and at the same node the final output command to the drive. The command follows the charging curve of the capacitor till it reaches the maximum value which is the first speed command for the first setting.

6. The automatic start and speed command apparatus of claim 2 wherein the second of two Dual Solid State Relays (SSR) comprises two independent, optically coupled, bidirectional MOSFET switches for switching to the second set point by energizing the input from the output command signal connected to the 555 timer circuit with a set preselected value for generating a specified time delay to energize the inputs of both of the Dual Solid State Relay comprising of two independent, optically coupled, bidirectional MOSFET switch and the second Dual Solid State Relay comprising of two independent, optically coupled, bidirectional MOSFET switch; and second set point is provided when the optically isolated relay of the first bidirectional MOSFET switch is energized and the contacts open on the first bidirectional MOSFET switch, and the normally open contacts close according to the configuration of said relay; and when the normally open contact closes a second voltages at the node which is electrically connected to the resistor and Zener diode and further wherein the resistor and the Zener diode coupled between the speed command output to the speed input of the drive.