12 results about "Pulse-width modulation" patented technology

A fan motor speed control circuit is disclosed. The circuit includes a digital/analog converting unit and a driving unit. The digital/analog converting unit takes charge of receiving a pulse width modulation (PWM) signal and converting it into a voltage signal. The driving unit is connected with the digital/analog converting unit in series for receiving the voltage signal, while the driving unit provides a first predetermined voltage level and a second predetermined voltage level as references. The fan motor is kept to run with a low constant rotation speed when the voltage signal level is higher than the first predetermined voltage level, with a full constant rotation speed when the voltage signal level is lower than the second predetermined voltage level, and with a variable rotation speed when the voltage signal level is lower than the first predetermined voltage level and higher than the second predetermined voltage level.

A circuit for controlling a voice-coil motor (VCM) may incorporate a pulse-width modulation driver to drive the VCM, a zero-current detector to determine whether the current across the VCM is zero, and a Back-EMF voltage detector to measure the voltage across the VCM when the current across the VCM is determined to be zero. The circuit may determine the current velocity of the VCM and use this information to control the velocity of the VCM.

The invention relates to a semiconductor lighting driving circuit which is compatible with a thyristor dimmer and a voltage input type dimmer. The semiconductor lighting driving circuit comprises a rectification filtering circuit, a power factor correction (PFC) circuit, a control circuit and a conversion circuit, wherein the rectification filtering circuit is used for converting an alternating current which comes from an alternating current power supply into a direct current; the PFC circuit is used for performing voltage reduction on the direct current; the control circuit is used for generating a pulse width modulation (PWM) control signal according to the direct current which is subjected to voltage reduction or an output voltage of the voltage input type dimmer; and the conversion circuit is used for supplying electric energy to a semiconductor lighting device according to the PWM control signal. The semiconductor lighting driving circuit is compatible with the thyristor dimmer and the voltage input type dimmer, can steadily operate in various kinds of dimming modes, and is high in generality. The semiconductor lighting driving circuit can independently operate, and the semiconductor lighting driving circuit and other circuit modules can conveniently form a product with high cost performance. Moreover, with the PFC circuit, the electromagnetic interference of the circuit can be remarkably reduced, so that the circuit operates more steadily and more reliably.

The invention relates to a digital-to-analogue conversion method based on a PWM (pulse width modulation) pin of a DSP (digital signal processor). The PWM pin in the DSP outputs a contact resistor R, a capacitor C is connected between the resistor R and a circuit GND (ground), and a public connecting point of the resistor R and the capacitor C serves as output; a signal requiring digital-to-analogue conversion is compared with a compare register in the DSP by the PWM pin in the DSP so as to obtain a high-frequency pulse waveform corresponding to the signal from the PWM pin, and then a waveform which is very close to the original signal can be obtained through the filter of the pulse waveform. According to the method, the analog of digital signals can be realized on the basis that the hardware cost is not increased nearly, and the complicated algorithm is not needed, and therefore, the danger caused by the online simulation run does not exist.

The invention belongs to the field of aviation permanent magnet synchronous motor control systems, and discloses an AD2S1210-based aviation permanent magnet motor rotor position angle redundancy control system and method. The space vector control FOC algorithm unit is used for generating six paths of PWM (Pulse Width Modulation) waves to drive the three-phase bridge type inversion module to be switched on and switched off by collecting armature current, rotor position angle and rotating speed information of the permanent magnet synchronous motor and adopting a rotating speed and current double-closed-loop control strategy, so that the permanent magnet synchronous motor is controlled to reach a target rotating speed or torque; the AD2S1210 rotary transformer decoding chip is used for collecting rotor position angle information and rotating speed information of a rotary transformer coaxially installed on the permanent magnet synchronous motor. The rotor position angle information and the rotating speed information are decoded and then sent to the position angle redundancy control algorithm unit; and the position angle redundancy control algorithm unit is used for judging the received rotor position angle information, outputting a correct position angle signal to the space vector control FOC algorithm unit, converting the received rotating speed information and outputting the converted rotating speed information to the space vector control FOC algorithm unit.

Provided is an electric motor comprising: a rotor having a rotating shaft inserted therein; a stator which is disposed around the rotor and provided with three-phase windings; an inverter including three sets of upper-arm switches and lower-arm switches corresponding to the three phases, and a freewheeling diode connected in parallel to each of the switches in the three sets of upper-arm switches and lower-arm switches; and a controller which performs pulse width modulation for the three sets of upper-arm switches and lower-arm switches by non-complementary switching at a constant carrier frequency. Each of the switches is a super junction field-effect transistor. The controller performs pulse width modulation at a duty ratio with an on-time longer than an on-time of the upper-arm switches when the upper-arm switches and lower-arm switches operate by complementary switching.