The present application provides a servo motor drive circuit and a 3D printing apparatus, a motion controller is configured to send a drive enable signal to the timer; a pulse period providing unit is configured to send a pulse period value to the timer and the first comparing unit at beginning of each pulse period; the timer is configured to perform initialization in response to the received pulse period value during enabling of the drive enable signal, perform cyclic timing by taking the pulse period value as a timing period, and send a timing duration to the first comparing unit; and the first comparing unit is configured to acquire current level information that satisfies a preset duty ratio according to the preset duty ratio, the pulse period value, and the timing duration, and send a drive signal to a servo motor according to the current level information.

A control device for a servo motor system is provided. The control device includes a segment parameter storage circuit, a velocity superposing circuit, a velocity transferring circuit and a pulse comparison circuit. The segment parameter storage circuit is electrically connected with the velocity superposing circuit and the pulse comparison circuit. The velocity transferring circuit is connected between the velocity superposing circuit and the pulse comparison circuit. The velocity superposing circuit updates a present velocity value according to a target velocity value and an increment. The velocity transferring circuit generates a PWM signal according to the present velocity value. The pulse comparison circuit transfers the PWM signal into a signal of a command pulse wave group and judges whether a pulse number of the PWM signal reaches a predetermined pulse number.

In described examples of methods and control systems to control a position and/or velocity of a machine, control circuitry is coupled to receive and dither a control signal, and to compute a control output value according to the dithered control signal and a control function. An inverter is coupled to the control circuitry, to control the position and/or velocity according to the control output value.

A programmable discrete input module is described. In one or more implementations, the programmable discrete input module comprises a pulse width modulation module configured to generate a pulse width modulated signal based upon an input signal and a pulse width demodulation module configured to generate a demodulated pulse width signal. An isolator is configured to isolate the pulse width modulation module and the pulse width demodulation module and to generate isolated modulated pulse width signal based upon the pulse width modulated signal for the pulse width demodulation module to generate the demodulated pulse width signal. The programmable discrete input module also includes a first comparator and a second comparator for comparing the demodulated pulse width signal with a respective programmable reference and a digital filter configured to filter a comparison signal output by the first comparator or the second comparator to generate a discrete input signal.

An electronic switch and an electronic device are disclosed. The electronic switch includes a trigger, a measurement device, a load control circuit, and the controller. The trigger switches on or off a circuit between a power supply and the electronic switch and generates the travel of the electronic switch. The measurement device is configured to measure working parameters of the power supply, the load and the trigger and to send the working parameters to the controller. The controller receives the working parameters and generates a control signal with a PWM signal. The PWM signal is obtained by adjusting the current control signal according to the working parameters. The control signal is sent to the load control circuit. The load control circuit controls the rotation speed of the motor in the load with the control signal.

An electronic switch control method is disclosed. The method comprises receiving the current working parameters of the electronic switch, then reading duty cycle parameters matching with the current working parameters; conducting a linear calculation with the duty cycle parameters and the working parameters to obtain a new duty cycle; adjusting the current control signal to obtain a PWM signal having the new duty cycle; and controlling the rotation speed of the motor in a load with the PWM signal. By reducing the volume of an electronic switch and achieving a long low-speed travel, the disclosure enables the user to work at an accurate working point with an electronic device.

A control system includes an electro-hydraulic servo valve configured to move about a plurality of positions in response to receiving an analog bi-polar current signal. An electronic field programmable gate array (FPGA) generates first and second digital pulse width modulation (PWM) signals according to an adjustable duty cycle. An electronic bridge circuit is in electrical communication with the FPGA to convert the first and second digital PWM signals into the bi-polar current signal. An electronic current sensing circuit is in electrical communication with the bridge circuit, the current sensing circuit configured to generate a digital feedback signal indicating an average current level of the bi-polar signal. The FPGA controls the duty cycle based on at least the average current level indicated by the digital feedback signal.

A programmable discrete input module is described. In one or more implementations, the programmable discrete input module comprises a pulse width modulation module configured to generate a pulse width modulated signal based upon an input signal and a pulse width demodulation module configured to generate a demodulated pulse width signal. An isolator is configured to isolate the pulse width modulation module and the pulse width demodulation module and to generate isolated modulated pulse width signal based upon the pulse width modulated signal for the pulse width demodulation module to generate the demodulated pulse width signal. The programmable discrete input module also includes a first comparator and a second comparator for comparing the demodulated pulse width signal with a respective programmable reference and a digital filter configured to filter a comparison signal output by the first comparator or the second comparator to generate a discrete input signal.

A programmable discrete input module is described. In one or more implementations, the programmable discrete input module comprises a pulse width modulation module configured to generate a pulse width modulated signal based upon an input signal and a pulse width modulation module configured to generate a demodulated pulse width signal. An isolator is configured to isolate the pulse width modulation module and the pulse width demodulation module and to generate isolated modulated pulse width signal based upon the pulse width modulated signal for the pulse width demodulation module to generate the demodulated pulse width signal. The programmable discrete input module also includes a first comparator and a second comparator for comparing the demodulated pulse width signal with a respective programmable reference and a digital filter configured to filter a comparison signal output by the first comparator or the second comparator to generate a discrete input signal.

An electronic switch and an electronic device are disclosed. The electronic switch includes a trigger, a measurement device, a load control circuit, and the controller. The trigger switches on or off a circuit between a power supply and the electronic switch and generates the travel of the electronic switch. The measurement device is configured to measure working parameters of the power supply, the load and the trigger and to send the working parameters to the controller. The controller receives the working parameters and generates a control signal with a PWM signal. The PWM signal is obtained by adjusting the current control signal according to the working parameters. The control signal is sent to the load control circuit. The load control circuit controls the rotation speed of the motor in the load with the control signal.