KR20020066000A - Srm driving circuit - Google Patents

Abstract

The present invention relates to an SM drive circuit, and to increase the conduction time of each phase to reduce the torque ripple. To this end, the present invention is a first capacitor for supplying a DC voltage obtained by smoothing the input power to the motor, N motor windings connected in parallel by the number of N phases in parallel, and the N motor windings connected in series up and down A plurality of PNP transistors and NMOS transistors, and a plurality of capacitors for supplying power when the plurality of NMO transistors are conductive, and conducting the plurality of PNP transistors with a charging current when the plurality of NMO transistors are turned off. And a plurality of freewheel diodes respectively connected between the emitters of the plurality of PNP transistors and the drains of the plurality of NMOS transistors, and between the collectors of the plurality of PNP transistors and the emitters of the plurality of NMOS transistors. Multiple freewheel diodes connected to each other and multiple resistors each detecting current flowing in each phase It is composed of.

Description

SM driving circuit {SRM DRIVING CIRCUIT}

The present invention relates to an SM drive circuit, and more particularly, to an SM drive circuit for reducing the torque ripple by increasing the conduction time of each phase.

Fig. 1 is a driving circuit diagram of an SLM having a general 6/4 structure. As shown in FIG. 1, the number of N phases in parallel with a DC link capacitor C for supplying a DC voltage obtained by smoothing an input power to a motor is shown in FIG. N motor windings (La, Lb, Lc) connected to each other, and the upper and lower switch elements (Q1a, Q1b, Q1c) connected in series with the motor windings (La, Lb, Lc) up and down (Q2a, Q2b, Q2c), the freewheel diodes FRD2, FRD4, FRD6 connected between the emitters of the upper switch elements Q1a, Q1b, Q1c and the emitters of the lower switch elements Q2a, Q2b, Q2c, and the upper collector. It is composed of a freewheel diode (FRD3, FRD5, FRD7) connected between the emitters of the lower switch elements (Q2a, Q2b, Q2c) and resistors (Rd1, Rd2, Rd3) for detecting a current flowing in each phase. The operation of the will be described.

First, when the DC voltage generated by smoothing the power input of the DC link capacitor C is supplied to the SRM, the SRM rotates, thereby connecting the photo interrupter and each phase inside the motor. By providing a disk having a slot, the position of the rotor is detected by the position sensor, and a signal corresponding to the detected position of the rotor is output.

If the signal for causing phase A to be induced is supplied to the bases of the upper and lower switch elements Q1a and Q2a connected in series with the motor winding La of the phase A, the phase and lower switch elements of the phase A are thereby Q1a) Q2a are turned on at the same time.

As the upper and lower switch elements Q1a and Q2a of the A phase are turned on, current flows to the motor winding La, thereby allowing electricity to be induced into the motor winding La of the A phase.

Thereafter, the phase and lower switch elements Q1a and Q2a of the A phase are turned off, and the upper and lower switch elements Q1b and Q2b connected in series to a motor winding Lb of the B phase in order to turn off the B phase. Are each supplied to the base of the.

At this time, the magnetic flux induced in the motor winding La of the phase A is removed by the freewheel diode (FRD3), DC link capacitor (C), freewheel diode (FRD2), the motor winding (La), the motor rotates smoothly, As a result, the upper and lower switch elements Q1b and Q2b of the B phase are turned on at the same time.

As the upper and lower switch elements Q1b and Q2b of B phase are turned on, current flows to the motor winding Lb, thereby allowing electricity to be induced to the motor winding Lb of the B phase.

Thereafter, the upper and lower switch elements Q1b and Q2b are simultaneously turned off, and a signal for turning on the C phase is supplied to the base of the upper and lower switch elements Q1c and Q2c. The magnetic flux induced by (Lb) is removed by the freewheel diode (FRD5), the DC link capacitor (C), the freewheel diode (FRD4), and the motor winding (Lb), so that the motor rotates smoothly. The lower switch elements Q1c and Q2c are turned on to induce electricity to the motor winding Lc.

Here, the position of the rotor is detected by a position sensor, and the detected rotor position signal is provided to a microcomputer (not shown).

The microcomputer then outputs a signal for controlling each phase.

However, in the conventional apparatus operating as described above, a large torque ripple is generated, especially in a low speed ALPM, the torque ripple is further intensified, thereby causing a large noise.

Accordingly, it is an object of the present invention to provide a driving circuit of SLM to reduce the torque ripple by increasing the conduction time of each phase through the pulse width control.

1 is a circuit diagram showing the configuration of a conventional SM drive circuit.

Figure 2 is a circuit diagram showing the configuration of the present invention SM drive circuit.

3 is a timing diagram in FIG. 2;

4 is a timing diagram of a signal for charging an initial capacitor in FIG.

5 is a flowchart of operation for charging an initial capacitor in FIG.

***** Description of the symbols for the main parts of the drawings *****

Q1a, Q1b, Q1c: PNP transistor M1, M2, M3: NMOS transistor

The present invention for achieving the above object is a first capacitor for supplying a DC voltage obtained by smoothing the input power to the motor, N motor windings each connected by the number of N phases in parallel, and the N motor windings When the plurality of NMOS transistors and the plurality of NMOS transistors are connected in series, the power is charged. When the plurality of NMOS transistors are turned off, the plurality of PNP transistors are charged with a charging current. A plurality of capacitors for conducting a plurality of capacitors, a plurality of freewheel diodes respectively connected between emitters of the plurality of PNP transistors and drains of the plurality of NMOS transistors, collectors of the plurality of PNP transistors, and a plurality of N Multiple freewheel diodes connected between the emitters of the MOS transistors and the currents flowing in each phase Shipping is characterized in that it is configured as a plurality of resistors.

Hereinafter, with reference to the accompanying drawings, the operation and effects of the embodiment of the SM drive circuit according to the present invention will be described.

FIG. 2 is a circuit diagram showing an embodiment of a driving circuit of the present invention, in parallel with a DC link capacitor C1 for supplying a DC voltage obtained by smoothing an input power to a motor, as shown in FIG. N motor windings (La, Lb, Lc) connected as many as N phases, PNP transistors (Q1a, Q1b, Q1c) and NMOS connected in series with the motor windings (La, Lb, Lc) When the transistors M1, M2, M3 and the NMO transistors M1, M2, M3 are turned on, the power is charged. When the NMOS transistors M1, M2, M3 are turned off, the charge current is driven by the charging current. Between capacitors C2, C3 and C4 which conduct transistors Q1a, Q1b and Q1c, and the emitters of the PNP transistors Q1a, Q1b and Q1c and the drains of enMOS transistors M1, M2 and M3. The freewheel diodes FRD2, FRD4 and FRD6 connected to the collectors and the collector and enmost of the PNP transistors Q1a, Q1b and Q1c. The freewheel diodes FRD3, FRD5, and FRD7 connected between the emitters of the transistors M1, M2, and M3, and resistors Rd1, Rd2, and Rd3 which detect currents flowing in the respective phases, are configured as described above. Describe the operation.

First, when the DC voltage generated by smoothing the power input of the DC link capacitor C1 is supplied to the SRM, the SRM rotates, thus connecting the photo interrupter and each phase inside the motor. The position of the rotor is detected by the position sensor by installing a disk having a slot that is closed.

Here, when the process of phase A is induced, first, a microcomputer (not shown) senses a position signal as shown in FIG. When applied to the NMOS transistor M1, the NMOS transistor M1 is turned on to charge the capacitor C2, and the PNP transistor Q1a is also turned on so that the motor winding La of FIG. A phase voltage as shown in (c) is applied, and a phase current as shown in Fig. 3D is detected at the resistor Rd1.

At this time, when the N-MOS transistor M1 of the A phase is turned off, a current charged in the capacitor C2 flows through the PNP transistor Q1a so that the PNP transistor Q1a does not perform high frequency switching. do.

Thereafter, the A phase transistor M1 of the A phase is turned off and a pulse width modulation signal for inducing the B phase is applied to the gate of the NMOS transistor M2 connected in series with the motor winding Lb of the B phase. The magnetic flux induced in the motor winding La of the phase A is removed by the freewheel diode FRD3, the DC link capacitor C1, the freewheel diode FRD2, and the motor winding La, and the motor rotates smoothly.

Accordingly, the NMOS transistor M2 is turned on to charge the capacitor C3, and the PNP transistor Q1b is also turned on so that a current flows in the motor winding Lb. It becomes possible to induce electricity to Lb).

Thereafter, the phase A enMOS transistor M2 is turned off and a pulse width modulated signal for inducing the phase C is applied to the gate of the enMOS transistor M3 connected in series with the motor winding Lc of the phase C. The magnetic flux induced in the B-phase motor winding Lb is removed by the freewheel diode FRD5, the DC link capacitor C1, the freewheel diode FRD4, and the motor winding Lb, and the motor rotates smoothly.

Accordingly, the NMOS transistor M3 is turned on to charge the capacitor C4, and the PNP transistor Q1c is also turned on so that a current flows in the motor winding Lc. It becomes possible to induce electricity to Lc).

Here, FIG. 5 is a flowchart illustrating operation in which the capacitors C2, C3, and C4 are not initially charged. That is, the microcomputer (not shown) may detect an initial capacitor (a) when a position signal as shown in FIG. In order to charge C2 to C4), the capacitors C2, C3, and C4 are charged by conducting each phase of the MOS transistors M1, M2 and M3 with a pulse width modulation signal as shown in FIG. At the same time, the PNP transistors Q1a, Q1b, and Q1c are also turned on, and at this time, voltages as shown in FIG. A phase current as in (d) is detected.

Thereafter, when the set time has elapsed, a normal pulse width modulated signal is output and the above-described operation is performed to induce each phase.

As described in detail above, the present invention does not require a separate drive circuit for switching a separate power supply and an upper switch, thereby reducing costs, and further increasing torque ripple by lengthening the conduction time of each phase switch through pulse width control. By reducing it, there is an effect of reducing the noise generated when driving the SM.

Claims (3)

A first capacitor for supplying a DC voltage obtained by smoothing the input power to the motor, N motor windings connected in parallel with each of the N phases, and a plurality of PNP types connected in series with the N motor windings. A plurality of capacitors for conducting the transistors and the MOS transistors, the plurality of NMOS transistors, and the plurality of capacitors to conduct the plurality of PNP transistors with a charging current when the plurality of NMOS transistors are turned off. A plurality of freewheel diodes respectively connected between the emitters of the PNP transistors and the drains of the plurality of NMOS transistors, and a plurality of freewheel diodes respectively connected between the collectors of the plurality of PNP transistors and the emitters of the plurality of NMOS transistors It is composed of a freewheel diode and a plurality of resistors for respectively detecting the current flowing in each phase. SM drive circuit. 2. The SM driving circuit according to claim 1, further comprising a microcomputer which receives a position signal sensed by the position sensor and outputs a pulse width modulated signal for controlling the on / off of the NMOS transistor accordingly. . The pulse width modulation signal of claim 2, wherein the microcomputer applies the pulse width modulation signal to the enMOS transistors of each phase for a predetermined time when the position signal is detected and turns on the capacitor to charge the capacitor. An SM drive circuit for controlling the on / off operation of each phase of the enMOS transistor.