JPS61251444A - Motor driving system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive system for use with an electric motor. DC motors have characteristics that make them particularly suitable for drive systems that require repeated starting and stopping operations.

Typical applications for such drive systems are hoists, elevators, many types of industrial machinery, and various vehicles.

However, it has been found that for all electric motors, the power consumption during acceleration, especially zero force), is much greater than the power consumption required during steady-state operation. Operation of such motors under conditions requiring repeated start-stop functions therefore involves some excessive power consumption.

Many attempts have been made to reduce this excessive power consumption during starting, ie, acceleration from zero. One approach is to provide a motor with an armature with multiple windings that can be connected or disconnected at various speeds.

A more complex version is the Ward-Leonard system, which uses a shared electric motor and generator, but is expensive and not suitable for general use.

Other systems use two or more separate windings, but
Only limited results can be obtained. Another approach is to provide what are effectively two separate motors, with the armatures actually coupled in tandem on the same axis, where low and high speed operation is required, such as in elevator or hoist motors. , it was all about providing two-speed operation.

The utility of such a system is somewhat limited, and the improvement over using a single electric motor is very limited.

Moreover, since this method effectively uses simple two-speed operation, it is generally not possible to provide smooth, continuous acceleration over a wide speed range, and in fact, it is not possible to provide smooth, continuous acceleration over a wide speed range, and in fact reduces power consumption fluctuations. This is known to occur.

From the point of view of economy and flexibility, to provide smooth and continuous acceleration from zero force 1 to the required maximum value while keeping the variation of power consumption to a minimum, while at the same time providing such advantages within a reasonable price. It is clearly desirable to provide an electric drive system that allows for

The invention therefore includes the following electric drive system. That is, the ratio of a first electric motor having a predetermined output rating to a first drive shaft to which the electric motor is connected; and an output rating of the first electric motor having a predetermined output rating is about 1. 5:1 to 3
:l, preferably 2:l; and a second drive shaft including a sleeve to which said second motor is connected and through which said first drive shaft extends concentrically. a sun gear to which the first shaft is directly connected for driving; a ring gear (internal gear) to which the second shaft is directly connected for driving; a plurality of mating planetary gears, an output drive coupled to and adapted to be driven by the planetary gears, and a ring gear configured to restrain rotation of the ring gear in one direction while responsive to drive by the second electric motor in the opposite direction; an electric drive system having a planetary gear arrangement including a one-way rotation restraint coupled to the ring gear to allow free rotation of the ring gear;

The invention also provides a method of operating an electric drive train.

Various innovations that characterize the invention can be found in the claims appended hereto. For a better understanding of the present invention, its operational advantages, and the specific objects achieved by its use, reference should be made to the accompanying documents and description that illustrate and describe preferred embodiments of the invention.

As shown, this preferred embodiment of the invention comprises a first housing (12) carrying a fixed value I, the housing being mounted on a suitable support (not shown) known in the art. It has an electric motor α [.The rotor scream is inside the sleeve (11
is keyed to the drive connection.

The electric motor αQ has a predetermined horsepower, for example 2 horsepower, and is a DC motor of suitable design.

A second, larger electric motor having a housing mounted on a suitable known mount or framework (not shown);
is also provided. A normal stator C inside the housing (2)
'41, and a rotor (E) coupled to the shaft (C). The axle includes a cylindrical sleeve member that is concentric with the axle and exerts a force S around it, and the axle α barrel is driven by an electric motor a, and the axle is driven by an electric motor (2I). .

The electric motor has a larger default horsepower rating, even Jf
It is desired that the motor be a DC motor of suitable design, with a horsepower of 1.5 g horsepower.

Of course, the motors (10, 20) shown are purely illustrative, as they incorporate features normally found in motors (10, 20) used for any particular application. , does not have any restrictions.

To couple the two electric motors (10, 20), shafts 0 and 3 are both connected to a planetary gear set in the housing Gυ.

coupled to the sun gear C32 of the shaft a pull gear device (to),
The shaft (to) is the ring gear (internal gear) of the same gear device (to)
Combined with (b).

A plurality of planetary gears (to) rotating between the sun gear t3 and the ring gear (b) are attached to a common driven member (to), which is then typically driven by an output drive shaft or the like. The output drive device 11t is connected.

It is desirable to provide a device that holds the ring gear (b) so as not to rotate in one direction while freely rotating it in the opposite direction according to the rotational output of the electric motor (2II).

A one-way rotation restraint device (4) of suitable design is therefore provided, substantially resembling a one-way clutch.

In the illustration, such a one-way rotation restraint device (4) is shown acting directly on the ring gear, but it is clear that this is merely an example.

Intermediate # (44 may act similarly on the shaft, or on any other member attached to the shaft), or in any other manner.

Rotation restraint device (42 is an outer ring (4a1 intermediate O-ra race) fixed to the housing Oυt, and a ring gear (
(b) has an inner inclined ring fixed to the inner side. One-force one-way restraints are commonly used commercially in transmissions and are known as sprag clutches.

No matter how such a one-way restraint device (42) is installed, the ring gear (b) is free to rotate in only one direction in response to drive by the electric motor (a).

When the electric motor (to) does not work, the ring gear (b) cannot rotate in the opposite direction due to the action of the restraint device.

The restraint system (42) is normally not provided with any actuating device; it is substantially self-adjusting and functions automatically in a known manner.

In operation, the electric drive system is assumed to be installed in a vehicle, eg, a road vehicle similar to an automobile powered by a storage battery or other power source.

When starting from zero rpm, only the electric motor (11) is activated. When power is applied to the electric motor αQ, it starts rotating the sun gear Oa via the shaft 08. Initially, the power requirement of motor aC is high, but according to the predetermined curve for that motor, it decreases rapidly until a high efficiency rotational speed is reached. However, since the power rating of the electric motor αq is relatively low, the excessive power consumption in this short period of time is comparatively small.

Rotation of the sun gear 0a causes rotation of the planetary gears, while the ring gear 0a is held in the stopped position by a restraint device (42).By providing an appropriate gear ratio, the rotation of the planetary gears The output shaft (41) is rotated at a reduction ratio of approximately 3:1 with respect to the rotational speed of a8.

Therefore, the electric motor α1 itself has a mechanical gain due to the above-mentioned reduction ratio of 3:1, and provides initial acceleration of the vehicle starting f)) through the planetary gear system (to).

In this way, the electric motor (IQ) uses the available power economically to rapidly reach maximum design rpm while producing acceleration of the vehicle up to the speed limit.

Once motor α1 reaches maximum rpm, or an efficient operating rpm range determined by the design of the motor itself, power is supplied to motor 1. The electric motor (A) is much larger and in fact has a rated output twice that of the electric motor (A). The required power is electricity) I
It must be big. Therefore, in order to reduce the load on the motor and reduce the power demand during starting, the motor Q1 is applied at a rate such that the motor can rapidly accelerate to the output speed, i.e. the speed at which the output shaft is currently operating. Reduces the power of and supplies power to electric motor ■. During this short transient period, the speed of the output shaft is almost constant, and the load shared between the motor (II) and the motor (2) changes in proportion as the motor (2) accelerates.

The electric motor (1) drives the shaft (3) to cause the rotation of the ring gear (2) in the same direction as the shaft α barrel, and the electric motor 4 thus accelerates under almost no load. Rotation of the ring gear causes rotation of the planetary gears, which revolve around sun gear C33 while sun gear 02 is actually decelerating.

Thus, during acceleration of the electric motor (4), the rpm of the output shaft (4G) remains stable over its initial, somewhat inefficient operating range.

As soon as the motors reach a more efficient operating rpm range, power is applied to both motors (10, 20
).

The power to both motors (10, 20) is adjusted so that the two motors (10, 20) enter a synchronized state in which they are rotating at the same speed as quickly as possible, so that the entire planetary gear system (
) rotates as a single unit, and the two shafts (18, 28) and the output shaft (40) rotating concentrically and at the same rpm effectively create a speed ratio of 1:l.

Once the two motors are balanced and synchronized, the power to the two motors 1 can be increased simultaneously to their maximum value so that the two motors 1 have maximum output at the same time.

The excessive peaks or step changes in power consumption normally experienced when accelerating a large electric motor (such as 7) to an efficient operating rpm range are effectively reduced or smoothed out; , it can be seen that relatively small power consumption is required when accelerating the smaller electric motor Ql from zero force to the efficient operating range.

At the same time, along with the output of the two electric motors, by optimizing the gear ratio of the planetary gear set, the planetary gear set is effectively fixed together so that the two motors drive together. It is possible to obtain a system in which the two electric motors can operate at maximum power.

Referring to Figure 2, the lower curve is that of motor αQ,
The upper curve shows that of two electric motors (10, 20).

The test was conducted by connecting the output shaft (41) to a dynamometer.

At the same dynamometer settings, readings were taken for the case of the electric motor σQ alone and for the case of the electric motor OI and the electric motor factor in combination.

This type of motor typically has a maximum rpm in the region of 3.00 Orpm or higher.

This type of motor has nearly linear operation over the range of its performance curve. It consumes very high power at low rpm, then rapidly becomes progressively more efficient (7 J) at higher rpm.

Although various circuits, and in many cases simple manual controls, may be sufficient to provide the functionality described above, circuits particularly suited for this purpose are disclosed in a third aspect.

In this case, electric motor OI and electric motor
t (to) and the output axis (,1G).

Power is provided from a power source, which may be a series of batteries or any other suitable power source. The power supply is directly connected to the electric motor (10, 20) via a switch and power controller G.

The motors (10, 20) are of a type incorporating suitable sensing devices for reading the rpm of the respective motor in a known manner and require no further explanation.

The rpm or tachometer output of the electric motor (to, 20) is connected to a comparator circuit (54), which in turn is connected to a speed controller (2). It may also be fully automatic and incorporate a device for presetting the various desired speeds.Alternatively, the speed controller ((5) may be a manual regulator for changing the speed or other means such as an accelerator or an accelerator in electrically powered vehicles). It is also possible to have a speed regulator (58) similar to a pedal.

Power for operation of the speed controller and comparator is supplied from a power supply 61).

Furthermore, a connection is made between the tachometer signal of the electric motor αC and the speed controller (50).

In operation of this circuit, the first operation of the speed regulator causes the power controller φ to send power to the motor αq. The motor Ql then rapidly accelerates to its high efficiency operating rpm, and the tachometer or rpm signal is transferred from the motor (II power) to the speed controller (2) and also to the comparator (5IO).
sent to.

As soon as the speed controller (5ω) receives a signal indicating the desired rpm of the electric motor Ql, it automatically sends a signal to the comparator (54) to start comparing the tachometers or rpm signals of the electric engine and the electric motor (2).

When the electric motor is not operating, a very large error signal is generated by the comparator (5), which is transmitted to the speed controller (G). This is then transmitted to the switch/power controller (G).
52) Reduce the power supplied to motor α1 by commanding
Electric power is proportionally supplied to the motor recess.

At this time, the two rpm signals received by the comparator (54) are rapidly brought into tune, the error signal is zeroed out, and the appropriate signals from the speed controller (54) control the switch/power control. Balanced power is now sent from the motors (5) to both electric motors (10, 20).

The foregoing is a description of preferred embodiments of the invention, set forth by way of example only. The invention is not limited to any of the specific features described, but includes all modifications that fall within the scope of the claims.

[Brief explanation of drawings]

Figure 1 shows the electric drive system according to the present invention (side cross-sectional color power)
The second factor is a graph showing the power consumption curve, and FIG. 3 is a schematic circuit diagram. lO...First electric motor 18...Drive shaft 20.
...Second electric motor Imperial order...Between drive shafts...Planetary gear device 32...Sun gear 34...Ring gear 36...Planetary gear 40...Output drive device, 42...One-way rotation restraint Device 52... Switch/power controller 54... Comparator L/-956...
・Speed controller Kuo...Speed regulator T-Mom)
-rF+ (recommended shaft speed 1) FIG 2 FIG 3

Claims (8)

[Claims] (1) A first DC motor having a predetermined output rating, a first drive shaft to which the first motor is drivingly coupled, and a second DC motor having a predetermined output rating higher than that of the first motor. an electric motor; a second drive shaft including a hollow sleeve member to which the second electric motor is drivingly coupled and through which the first drive shaft extends generally axially; and a planetary gear arrangement. and a sun gear drive-coupled to rotate the first drive shaft in the forward direction; and a sun gear drive-coupled to rotate the second drive shaft in the forward direction. a ring gear (internal gear), a plurality of planetary gears meshing with both the sun gear and the ring gear, and an output drive coupled to the sun gear so as to rotate in unison around the sun gear; The ring gear is operatively coupled to the ring gear to restrict rotation of the ring gear only in the reverse direction and allows free rotation in the forward direction, so that the ring gear rotates in the forward direction under the action of the second electric motor. a one-way clutch-type rotation restraint device for allowing free rotation; an electric motor drive system; (2) further comprising an operation control device, the operation control device;
a first tachometer operatively coupled to said first electric motor and operative to provide a first speed signal indicative of a rotational speed of said first electric motor; a second tachometer operable to provide a second speed signal indicative of the rotational speed of the second electric motor; a second tachometer operably connected to the first and second tachometers; a comparator adapted to compare speed signals and provide an error signal indicative of a difference between the first and second speed signals; operably connected to the first and second motors; a switch/power controller operable to individually control power supply to each of the first and second electric motors; operably connected to the first tachometer, the comparator, and the switch/power controller; and enabling the switch and power controller to supply power to the first motor, and sending a signal to the comparator to activate the comparator when the speed of the first motor reaches a predetermined value; receiving an error signal from the comparator indicating a difference between the first and second speed signals, and causing power to be supplied to the second motor to reduce the error signal; and a speed controller operative to provide a control signal to the switch and power controller to reduce power supply. (3) The electric motor drive system according to claim 2, wherein the speed controller further includes a speed regulator that can be operated independently. (4) The motor drive system according to claim 1, wherein the ratio of the output rating of the second electric motor to the output rating of the first electric motor is about 1.5:1 to about 3:1. . (5) The ratio of the output rating of the second electric motor to the output rating of the first electric motor is about 2:1.
The electric motor drive system described in . (6) When the ring gear is stationary, the gear ratio between the first drive shaft and the output drive device is 3:1,
the sun gear such that the gear ratio between the first and second drive shafts and the output drive is 1:1 when the first and second drive shafts are rotating at the same speed; The electric motor drive system according to claim 1, wherein gear ratios of the planetary gear, the planetary gear, and the ring gear are determined. (7) a first DC motor having a predetermined output rating; a first drive shaft to which the first motor is drivingly coupled; and a second DC motor having a predetermined output rating higher than that of the first motor; an electric motor; a second drive shaft including a hollow sleeve member to which the second electric motor is drivingly coupled and through which the first drive shaft extends generally axially; and a planetary gear set; a ring gear drivingly coupled to the first drive shaft for rotation in a forward direction; a plurality of planetary gears meshing with both the sun gear and the ring gear; an output drive device coupled to the sun gear so as to rotate in unison around the gear; and an output drive device operably coupled to the ring gear to restrict rotation of the ring gear only in the backward direction and prevent rotation in the forward direction. a one-way clutch-type rotation restraint device that is not activated, thereby allowing the ring gear to rotate freely in the forward direction under the action of the second electric motor; The method includes the steps of: supplying power to the first motor to rotate the first drive shaft and the sun gear in the forward direction; and preventing the first drive shaft and the sun gear from rotating in the reverse direction by the restraint device. constraining a ring gear, and then powering the second electric motor to rotate the second drive shaft and the ring gear in the forward direction as soon as the rotational speed of the first drive shaft reaches a predetermined value. and increasing the power supply to the second electric motor until the first and second drive shafts rotate in the forward direction in synchronization, and increasing the power supply to the first electric motor. and reducing the supply of. (8) After the rotational speed of the first electric motor reaches the predetermined value, speed signals from first and second tachometers operably coupled to the first and second electric motors, respectively; providing an error signal indicative of a rotational speed difference between the first and second electric motors in response to the magnitude of the signal to reduce the error signal; 8. The method of claim 7, further comprising the step of controlling the supply of electrical power.