DE8905384U1 - Asynchronous motor for electronic speed control - Google Patents

Description

Electronicsril^geifl«VdWaCtflt"tQinbH & Co. KG

Upper Helweg 43a. D-4800 Bielefeld I.Tetafon (OS 21) 2 2013/2 3017, Telex 832 048 eraU d

_r , Bielefeld, 27 April 1989

Asynchronous motor for electronic speed control.

The invention relates to an asynchronous motor (ASM) for electronic speed control, in particular one designed for an extended control range in which creeping speeds are to be achieved without torque pulsation (tooth effect).

It is known to set the rotor slots at an angle to suppress the skidding effect. However, this leads to an increase in slip and thus to a deterioration in efficiency and power factor. This also results in a lower model utilization. Relay runners are also known.

The aim of the invention is to optimize ASM for electronic speed control in all respects, i.e. Expanding the control range, both up and down, avoiding torque pulsation, increasing the continuous torque, especially in the lower speed range, improving efficiency and power factor, increasing the starting and breakdown torque, thereby achieving a higher model utilization, which in turn results in a higher switching frequency, relieving the network or the supply lines of current fluctuations or current peaks and harmonic content, which in turn means that choke coils and their losses are no longer required. Furthermore, shielded cables are no longer required, and in some cases the external fans in the switch cabinets are no longer required. The cost savings sometimes occur twice because smaller electronics can be used for a smaller electric motor.

The optimization measures implemented so far have always been limited to a maximum of two points. The above statements enable a much more extensive improvement.

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Electronic-technology company GrfibH & Co. KG UpperHellweg43a,'Ch48b0Bielefeibi,Telephone(0521)2'2013/23017,Telex93204eerabicl

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Ref. G 89 05 384.2 Bielefeld, 06.07.1989

Asynchronous motor for electronic speed control

new page 2 of the description:

The solution to the problem is achieved in accordance with the features mentioned in the protection claims.

The advantages arise from the explanations in the task.

Details and results of the invention are given in the explanations of Figures 1 and 2.

Fig. 1 shows a motor plate with 36/44 slots,
Fig. 2 shows a motor plate with 24/18 slots.

Motor plates according to Fig. 2 are from the designs corresponding to the state of the art. This state of the art assumes that an ASM has a fixed operating point, which results from the frequency and number of pole pairs, minus slip.

However, if such an engine is used in the entire working area
If the motor is operated between zero speed and N3nn speed, the currents flowing in the motor winding have disturbing harmonic components that lead to a reduction in torque and the generation of noise. This limits the suitability as a variable speed drive and in borderline cases even makes it impossible.

If a motor plate as shown in Fig. 1 is used, significantly more favorable utility values are achieved.

The sheets shown were used for 2-pole ASM. For other pole numbers, the features according to the invention
The groove numbers are not absolute, they were only used to explain the measured values shown in Figures 3 and 4.

The suitability of engine sheets is best determined using a measuring technique.

As measurement-technical investigations have shown, the opinion held by experts that every ASM (normal motor) would be suitable for speed control is incorrect. The marginal comments made in the literature to date about parasitic currents in the limit range can have such a great influence on the entire system during speed control that the operational capability can no longer be guaranteed.

The frequently used approach of completely dispensing with ASM in such cases is considerably more costly than optimization in the manner described at the beginning.

Details of the oscillograms are explained directly in Figures 3 and 4.

ERA

· · I 1 ···■

Elektronl^egetaistpmetiH GhibH & Co. KG Upper HeHweg 43a, D-4800 Bielefeld 1 ', Telephone (05 21*) *2 2013/2 3017, Telex 932 048 erabi d

Bielefeld, 25.07.1989

Text for figure 3:

Experiment to determine the optimal number of grooves.

Upper curve: speed measured with gear pulse generator

60 pulses/min,

lower curve: current oscillogram no. 140389/1

2-pole motor No. 2050639 Type DNT 112L-21A-B

24/18 grooves,

Paper feed 200 mm/min, 15 mm = 0.5 A, 1.2 rpm Idle approx. 3.0 A, 10 mm = 150 periods

Text to figure 4;

Experiment to determine the optimal number of grooves.

Upper curve: speed measured with gear pulse generator

60 pulses/min,

''ntsre Kurvet Streit!

Oscillogram No. 140389/2 2-pole motor No. 2050638 Type DNT 112M-23A-B 36/44 slots,

Paper feed 200 mm/min, 15 mm = 0.5 A, 1.2 rpm Idle approx. 2.7 A, 10 mm = 150 periods.

Claims (2)

Protection claims: 1.) For electronic speed control with variable voltage characterized in that the stator winding is designed as a slit half-hole winding and that, when designed as a 2-pole motor, sheets are used which are usually used to manufacture 4-pole motors and that the squirrel-cage rotor is made of an aluminum alloy with increased resistance. 2.) Asynchronous motor according to claim 1.) characterized in that a second stator winding is accommodated in the slots, the number of poles of the second winding differing from the number of working poles.