U.S. Philips Corporation

Other

Hewlett-packard Company

Henricus C Buthker

Antonius A Marinus

Nicolaas Johannes Damstra

Marinus C Van Buul

Boyd N Shelton

Gerardus A Van Beijsterveld

Frans Pansier

A motor control device controls an electric 3-phase brushless d.c. motor (10) having a magnetic rotor (15) and three windings (11, 12, 13). The motor control device includes a detection unit (20) adapted to generate a commutation signal (21) on the basis of the back-emf voltage produced in the windings (11, 12 and 13). The motor control device further includes an output stage (30) having a first terminal (31) and a second terminal (32) for the connection of a power-supply source, outputs (33, 34, 35) for the connection of the windings (11, 12 and 13) and a number of semiconductor elements (36) for selectively coupling the terminals (31, 32) to the outputs (33, 34, 35) in dependence upon the commutation signal (21). The motor control device further includes a phase detector (40) adapted to generate a phase-error signal (43) which is representative of the phase difference between a sensor signal and a reference signal. The output stage (30) is arranged in series with a controllable power-supply stage (50) adapted to feed a bidirectional current (I) through the windings (11, 12, 13) via the outputs (33, 34, 35). The current (I) is controlled in dependence upon the phase-error signal (43) for driving the rotor (15) in a controlled manner, or for actively braking said rotor.

Motor control device apparatus for the recording and/or reproduction of

An arrangement for generating drive signals for a multi-phase d.c. motor having a plurality of windings, comprising a multi-phase inverter (10) which supplies the drive signals to the windings of the motor in a manner such that the windings are recurrently energized by the drive signals in a given sequence. At least one of the windings is not supplied with a drive signal at least during predetermined free periods. A phase detector (40) which, under control of the multi-phase inverter, samples the back-emf signals of these windings in order to obtain a phase-error signal. A low-pass filter (42) generates a control signal dependence upon the phase-error signal, and a controllable oscillator (44) generates a frequency signal whose frequency depends on the control signal. The timing of the multi-phase inverter drive signals supplied to the motor windings depends on the frequency signal. A phase-locked loop is formed by the multi-phase inverter, the phase detector, the low-pass filter and the oscillator. A lock detector (70) which, on the basis of information about the frequency and phase of the phase-error signal and information about the frequency and phase of the frequency signal, determines whether or not the phase-locked loop is locked in phase.

Arrangement for generating drive signals for a multi-phase d.c. motor,

An integrated circuit (1) includes a voltage-sensing circuit (2) and a current mirror (3) for sensing both a voltage (Vi) and a current (Ii) at one input terminal (T) of the integrated circuit. The voltage-sensing circuit (2) has an input which is connected to the input terminal (T) and an output which supplies a voltage level indication (Vu). The current mirror (3) has an input which is also connected to the input terminal (T), a reference terminal which is connected to a reference potential, and an output which supplies an output current (Iu). The input of the current mirror has a high impedance as long as the voltage level (Vi) is below a threshold voltage (Vth) of the current mirror (3). Within a voltage range determined by this threshold voltage (Vth), the voltage level indication (Vu) is a measure of the voltage level (Vi). The current mirror (3) becomes active and the output current (Iu) is a mirrored input current (Ii) if the voltage level (Vi) exceeds the threshold voltage (Vth). The threshold voltage may be determined by an input transistor (T1) of the current mirror (3). This input transistor (T1), which is arranged as a diode, starts conducting when the voltage level (Vi) reaches the threshold voltage (Vth) of this diode.

Current and voltage-sensing

A drive circuit for supplying drive signals to a plurality of windings of a multi-phase d.c. motor. The drive circuit comprises a multi-phase inverter which supplies the drive signals to the motor windings; a phase detector which samples the back-emf signal of a winding in order to obtain a phase-error signal; a low-pass filter which generates a control signal dependent upon the phase-error signal; and a controllable oscillator which generates a frequency signal whose phase and frequency depend on the control signal. The timing with which the multi-phase inverter supplies the drive signals to the windings is dependent on the frequency signal. The drive circuit further comprises a masking circuit for temporarily inhibiting the further processing of the phase-error signal by the low-pass filter, at least during the presence of a flyback signal in the phase-error signal, as a result of which the processing of the flyback pulses present in the phase-error signal is inhibited.

Drive circuit supplying drive signals to a plurality of windings of a

A PWM controlled multiphase DC motor apparatus has a multiphase DC motor, a current sensor, and a PWM controller. The DC motor has multiple windings which turn on and off during commutation at a commutation frequency. The current sensor is coupled to sense power supply current flowing in all windings of the DC motor. The PWM controller is coupled to control the DC motor using a PWM signal at selected PWM frequency with variable duty cycle. Using the feedback from the current sensor, the PWM controller maintains approximately constant torque in the DC motor by adjusting the duty cycle of the PWM signal. The PWM controller includes a soft switching circuit which manipulates a voltage used to generate the controlling PWM signal in a manner which causes linear stewing of currents in the windings during commutation. The linear current stewing occurs at a slew rate that is slow relative to the PWM frequency to thereby reduce torque ripple during commutation. The combined features of continuous PWM duty cycle control and linear current slewing during commutation significantly reduces torque ripple at the fundamental commutation frequency, as well as at the first few harmonics. A method for PWM control of a multiphase DC motor is also described.

Soft switching, PWM controller and method for reducing torque ripple in

Switched-mode power supplies in which a series arrangement of a bipolar transistor and a MOS field effect transistor is used are known and referred to as cascode circuits. In these circuits the bipolar transistor is switched (with the MOS field effect transistor) via the emitter instead of with the base. Since the collector current of the bipolar transistor may vary over a large range, the base should be proportionally driven to prevent the bipolar transistor from getting either above or below its normal operating range. By making use of an extra winding on a transformer arranged in series with the cascode circuit, a non-dissipative proportional drive of the base of the bipolar transistor is obtained. The extra winding is coupled to the base via an inductance.

Switch mode power supply with BJT/MOSFET cascode circuit

A power supply circuit includes a cascade arrangement of a full-wave rectifier and a first and a second switched voltage converter. The input terminals of the first voltage converter receive a rectified supply voltage. The second switched voltage converter has input terminals connected to a first storage capacitor of the first voltage converter. The second voltage converter includes the output terminals of the power supply circuit. A control circuit controls the period of conductance of the controlled switches of the switched voltage converters with a switching period which is much shorter than the cycle period of the AC supply voltage. A first inductive element is connected via a first controlled switch across the output terminals of the full-wave rectifier during a part of the switching period. A first rectifier diode is connected to the first inductive element so that the diode is non-conducting during this part of the period and, during the period when the diode is conducting, the diode current does not flow to the input terminals of the first switched voltage converter.

Growing community of inventors

Mierlo, Netherlands

Henricus C Buthker