The semi-cross interlocked circuit with unbalanced voltage cyclic current check function for the speed difference permitted commutator type motors

Abstract: At least two commutator type motors are arranged to reduce cyclic voltage imbalances or oscillations by connecting a check diode in series with the armature of each motor, and by partially interlocking the motors by connecting the series winding of a neighboring motor to the end of the armature which is not connected to the check diode.

Description: This invention relates to a partially-interlocked motor control circuit for plural commutator type motors. This type of motor is described in EP-A-0596170 and US-A-2070323. The present invention provides a partially-interlocked motor control circuit for plural commutator type motors, the control circuit comprising: first and second armatures each having first and second ends; a first diode connected to the first end of the first armature, and a second diode connected to the first end of the second armature; a first series field winding arranged to interact magnetically with the first armature to cause the first armature to rotate when a current is present in the first series field winding, and a second series field winding arranged to interact magnetically with the second armature to cause the second armature to rotate when a current is present in the second series field winding; and the first series field winding being series connected to the second end of the second armature, and the second series field winding being series connected to the second end of the first armature; characterised by a third series field winding arranged to interact magnetically with the first armature and connected between a terminal of the power supply and each of the first and second series field windings; and a fourth series field winding arranged to interact magnetically with the second armature and connected between a second terminal of the power supply and each of the diodes. The invention will now be described in greater detail, by way of example, with reference to the drawings, in which- Figure 1 is a schematic diagram of a basic partially-interlocked multiple motor control circuit with oscillator damping functions for speed difference permitted commutator type motors according to the present invention; Figure 2 is a schematic diagram of an example of a parallel combination of partially-interlocked series motors; and Figure 3 is a schematic diagram showing a variation of the embodiment of Figure 2, in which the sequential order of the respective series windings are exchanged. Conventionally, when two commutator type series motors are driven in parallel, balanced operation between the two motors is difficult to obtain, particularly when the ratio between the two respective series motor torques and speeds is very large. In contrast, for practical applications when more balanced driving characteristics are required, such as for electrical carrier loads, the invention provides a partially cross-interlocked circuit with oscillation damping functions to permit speed differences with a more balanced operating characteristic of the series excited commutator type motors. The preferred circuit is characterised in that the armature windings of the two or more series excited motors, or double excited motors with series excited windings, are series combined with a check diode in the current flow direction, and further series combined with the series winding of the motor itself, which in turn is partially cross-interlocked or series combined with the series winding of the neighbouring motor, and further connected with a voltage balancing line including a voltage balance resistance connection at the ends of the respective armatures which are not connected to the check diodes. This has the effect of reducing the armature current cycling to improve the operating characteristics of the original series or parallel combinations by improving torque distributions due to different loading conditions or regenerated braking functions. Figure 1 is the basic circuit schematic diagram of a preferred partially cross-interlocked circuit with unbalanced voltage cyclic current check functions for commutator type motors in which speed differences are permitted. This figure shows, by way of example, two series excited motors, the principal components of which are as follows: A first motor including a first series excited winding S111, a second series winding S112 and an armature A111; A second motor including a first series winding S121, a second series winding S122 and an armature A121. The "a" end of the first series excited winding S111 of the first motor is connected to the positive end of the power source, and the "b" end of the winding S111 is connected to the "m" end of the second series excited winding S122. The "n" end of the winding S122 is further connected to the "c" end of the first motor armature A111, and the "d" end of the armature A111 is series combined with a diode CR111 in the current flow direction, the diode CR111 being further connected to the "x" end of first series excited winding S121, and the "y" end of the winding S121 is connected to the negative end of the power source. The "e" end of the second series excited winding S112 of the first motor is also connected to the "b" end of the first series excited winding S111, while the "f' end of the winding S112 is connected to the "v" end of the armature A121. The "w" end of the second motor armature A121 is series combined with a diode CR121 in the current flow direction, the diode CR121 being further connected to the "x" end of the first series excited winding S121, and the "y" end of the winding S121 is connected to the negative end of the power source. The current values along the respective first series excited windings S111 and S121 of the motors are the same, and are the sum of the currents through the second series excited windings S112 and S122 respectively. The diode CR112 is a common flywheel diode which is reversely parallel combined between the "b" and "x" ends of the first series windings. Because the respective first series excited windings S111 and S121 of the two motors share the same current value, and the current value is the sum of the two armature current values, when the first motor load is increased, the first motor rotational speed is lowered, so is the counter emf, so that the current of the first motor is increased, and the series excited field winding currents of both motors are increased at the same time, causing the second motor rotational speed to also be lowered. Compared to a conventional parallel combination of series excited motors, the preferred circuit furnishes smaller rotational speed differences between motors, resulting in improved stability. Conversely, when the load of the second motor is increased, the first motor will react in the same way as the second motor reacts when the load on the first motor is increased. The current value along the common series excited winding is the added value from the respective series combined motor armatures, and is different from that a conventional series excited motor, while the current values along the second series excited windings are respectively equal to their series combined armature current values, as a result of which the first series excited windings of the motors have larger current values. The circuit of Figure 1, which is the basic circuit of the preferred embodiment, is in summary a circuit in which the respective motors are installed with second series excited windings to have the same current values as those of the respective armatures, such that, when the excitation current of one of the second series excited windings is increased due to an increased motor load, the neighbouring motor excitation is caused to increase correspondingly. Figure 2 is a schematic diagram of a variation the preferred embodiment of Figure 1, in which:- Two series excited motors are respectively provided with first series excited windings S211, S221, and second series excited windings S212, S222. The first series excited winding of each motor is series combined with its own armature, and is series combined with the second series excited winding of the neighbouring motor, and then is mutually parallel combined. The ends of the armatures A211 and A221 are series combined with check diodes CR211, CR221 respectively, and then are commonly connected to the negative end of the power source. The other end of the armature A211 is series connected to its own first series excited winding S211, the second series excited winding S222, and the positive end of the power source. The other end of the armature A221 is series connected to its own first series excited winding S221, the second series excited winding S212, and the positive end of the power source. Then a voltage balancing line may be installed between the two ends of the armatures A211 and A221 or, as indicated by the dashed line, is installed between the connecting point of the series excited windings S211 and S222. As a result, the respective connecting point of the series windings either form pairs of series-connected windings which are mutually parallel combined, or pairs of parallel-connected windings which are mutually series combined. A flywheel diode CR200 is installed between the voltage balancing line and the negative end of the power source to absorb the power pulsation for stable operation. More generally, the motor set can be comprised of two or more motors, in which the first series excited winding of each motor is installed, as described above, to be series combined with its own armature, and then series combined with the second series excited winding of the neighbouring motor in sequential order, the last motor armature being series combined with the second series excited winding of the first motor to form a closed ring arrangement of partial cross-connected series combinations. The non-partial cross-connected end of each armature is installed with diodes in the current flow direction, and is parallel connected to the negative end of the power source as described above. Figure 3 illustrates an example of the circuit of Figure 2 in which the sequential orders of the respective series windings are exchanged, the circuit being comprised of the following elements:- The ends of the respective armatures A411 and A421 are respectively series combined with check diodes CR411 and CR421, which are mutually connected to the negative end of the power source. The other end of the armature A411 is series connected to the second series winding S422 of the neighbouring motor, and then is further series connected with the first series winding S411 to the positive end of the power source. The other end of the armature A421 is series connected with the second series winding S412 of the neighbouring motor, and is further series connected with its own first series winding S421 to the positive end of the power source. One voltage balancing line can be connected to either end of the armatures A411 and A421, or can be connected (as shown in dashed lines) between the connecting point of the series windings S411 and S422 and the connecting point of the series windings S412 and S421 to form pairs of windings in a manner similar to the arrangement of Figure 2, described above. One flywheel diode CR400 is parallel combined between the voltage balancing line and the negative end of the power source. More generally, the motor set of the embodiment of Figure 3 can be comprised of two or more motors, wherein one end of each armature is installed with diodes in the current flow direction, and is commonly connected at the negative end of the power source. The other end of each armature is series combined with the second series winding of the neighbouring motor, and is further series combined in sequential order with the first series winding of the motor itself. The first motor armature is series combined with the second series winding of the last motor, and is further series combined with first series winding of the first motor itself, to thereby form a closed loop type arrangement of partially-cross-linked series combinations to provide mutual interactions.

Claims: A partially-interlocked motor control circuit for plural commutator type motors, the control circuit comprising: first and second armatures (A111 and A121) each having first and second ends (d, w, and c, v); a first diode (CR111) connected to the first end (d) of the first armature, and a second diode (CR121) connected to the first end (w) of the second armature; a first series field winding (S112) arranged to interact magnetically with the first armature to cause the first armature to rotate when a current is present in the first series field winding, and a second series field winding (S122), arranged to interact magnetically with the second armature to cause the second armature to rotate when a current is present in the second series field winding; and the first series field winding being series connected to the second end (v) of the second armature, and the second series field winding being series connected to the second end (c) of the first armature; characterised by a third series field winding (S111) arranged to interact magnetically with the first armature and connected between a first terminal of the power supply and each of the first and second series field windings; and a fourth series field winding (S121) arranged to interact magnetically with the second armature and connected between a second terminal of the power supply and each of the diodes. A partially-interlocked motor control circuit as claimed in claim 1, further comprising a flywheel diode (CR112) connected between the third and fourth series field windings (S111 and S121).

Inventors: YANG TAI-HER, YANG, TAI-HER
Applicants: YANG TAI-HER, YANG, TAI-HER
Application year: 1995
Main classification: H02P7
IPC codes: H02K23, H02P5