CN103095187A

CN103095187A - Motor starter

Info

Publication number: CN103095187A
Application number: CN2012104308385A
Authority: CN
Inventors: K.克里斯坦森; U.格罗思; T.伯特尔森; D.霍马思
Original assignee: Secop GmbH
Current assignee: Secop GmbH
Priority date: 2011-11-01
Filing date: 2012-11-01
Publication date: 2013-05-08
Also published as: DE102012020102A1

Abstract

An AC motor comprising a main winding, an auxiliary winding and a switching circuit is disclosed. The switching circuit switching circuit comprises a voltage divider and a bidirectional triode thyristor (or other AC switches) i.e. triac. The voltage divider comprises a resistor with positive temperature coefficient. When a system is started (the system is cold), a voltage enough to switch on the bidirectional triode thyristor so as to enable currents to pass through the auxiliary winding is generated on the grid electrode of the bidirectional triode thyristor. However, after a while, temperature on the resistor of the PTC raises, voltage on the grid electrode of the bidirectional triode thyristor drops, and thus the bidirectional triode thyristor breaks. A capacitor (52) is used for coupling the output end of the voltage divider and the grid electrode of the bidirectional triode thyristor, and has the effect of reducing switching noises on the zero crossing point of an AC power source.

Description

Motor starting device

Technical field

The present invention relates to starting device; Relate in particular to, for example, be used in positive temperature coefficient (PTC) starting device in single-phase AC motor.

Background technology

Known single-phase AC motor is furnished with two windings: main winding and auxiliary winding.As institute is well-known in the prior art, when auxiliary winding is used in starter motor.After the startup stage having completed, will assist the winding outage, and allow main winding take over the operation of AC motor.

Some known AC motors utilize positive temperature coefficient (PTC) resistor to regulate the use of auxiliary winding.

Fig. 1 is the schematic circuit of the known motor system that totally represents with label 1.Electric system 1 comprises AC power supplies 2, switch 3, main winding 4, auxiliary winding 6 and positive temperature coefficient (PTC) resistor 8.Auxiliary winding 6 and PTC resistor 8 series connection and in parallel with main winding 4 mutually.Switch 3 is to connect like this: when closure, electric current can flow to main winding and flow to auxiliary winding/PTC resistor pair from power supply 2.

Electric system 1 is suitable as compressor, for example, and the compressor in refrigerating system.When the part as compressor was used for refrigerating system, switch 3 is thermostat normally, made the temperature that depends on that thermostat is measured, and switched on and off compressor by thermostat 3.

In general, when switch 3 became closure state from open mode, PTC resistor 8 was cold, therefore had less resistance (the perhaps order of magnitude of 25 ohm).Therefore, corresponding larger electric current can flow through auxiliary winding 6 and PTC resistor 8.

Large electric current flows through PTC resistor 8 and causes that resistor heating.Because PTC resistor 8 has positive temperature coefficient, so raising with temperature, resistance increases, make when electric current passes through PTC resistor 8, as time goes by, the resistance of PTC resistor 8 increases (perhaps reaching maximum 2 kilohms).Certainly, along with resistance increases, the electric current (therefore by assisting the electric current of winding 6) by resistor reduces.

Therefore, along with switch 3 closures, when resistor 8 when being cold, sizable electric current is by auxiliary winding, but when resistor 8 is heat, only has little electric current by assisting winding.

Suppose switch 3 opened significant period of time.Suppose now that switch is closed.The closure of switch will cause sizable electric current by motor 1 main winding 4 and auxiliary winding 6 both.Resistor 8 guarantees that the electric current in auxiliary winding has the phase place different from the electric current in main winding 4.Consequently, can generate the shifting magnetic field and drive induction machine.Therefore, auxiliary winding can be used for starter motor.In case motor movement gets up, just no longer need auxiliary winding.Therefore, circuit 1 is arranged to the electric current that reduces in auxiliary winding 6, and makes the operation of 4 gas-distributing motors 1 of main winding.

As mentioned above, when the PTC resistor is heat, by the electric current less of auxiliary winding 6.But, that electric current can not be reduced to zero, and therefore auxiliary winding 6 can power consumption.This electric power has been wasted.Obviously, generally all wishes to reduce except the startup stage other times flow through the electric current of assisting winding 6.

Fig. 2 totally represents, attempts a kind of circuit diagram of known variant of the said motor system 1 of the electric weight that reduces to waste with label 10.Electric system 10 comprises AC power supplies 2, switch 3, main winding 4, auxiliary winding 6 and the PTC resistor 8 of foregoing circuit 1.Circuit 10 also comprises switching device 11.

Switching device 11 comprises the first resistor 14, the second resistor 16 and bidirectional triode thyristor 12.Bidirectional triode thyristor 12 is TRIAC normally, and the below is referred to as TRIAC.

The first resistor 14 and the second resistor 16 form the voltage divider between the second end that is connected to auxiliary winding 6 and power supply 2.The first resistor 14 is PTC resistors.When switch 3 was closed, the voltage on the voltage divider mid point was the part of the AC voltage that provides of voltage source 2, and that ratio depends on

resistor

14 and 16 relative resistance and the resistance of auxiliary winding 6 to a great extent.Along with the resistance increase (along with temperature raises) of the first resistor 14, the voltage drop on the voltage divider mid point is to the low ratio of AC voltage source.Therefore, the voltage on the voltage divider mid point raises along with temperature and descends.

The mid point of voltage divider and the gate input of TRIAC 12 are coupled.When PTC resistor 14 be cold (make voltage on the TRIAC grid be the AC voltage that provides of power supply 2 relatively at high proportion) time, TRIAC is switched on, and makes electric current pass through auxiliary winding 6 and TRIAC 12.When PTC resistor relatively hot (making voltage on the TRIAC grid is the relatively low ratio of the AC voltage that provides of power supply 2), TRIAC disconnects.

Again suppose switch 3 opened significant period of time.Suppose now that switch is closed.Because PTC resistor 14 is cold, so the voltage on the voltage divider mid point will be high enough to connect TRIAC 12.Therefore, quite large electric current is by auxiliary winding 6.As time goes by, the resistance of PTC resistor 14 increases, so the voltage drop on the grid of TRIAC 12.To lower than the switching threshold of TRIAC the time, TRIAC disconnects, and flows through main winding 4 from most of electric current of AC power supplies when voltage drop.

Resistor 14 can have the resistance from 2 kilohms (when relatively cold) to 10 kilohms (when relatively hot).So the resistance that is in the voltage divider of the switching device 11 of (when TRIAC disconnects) on high temperature is significantly greater than the resistance of the resistor 8 in foregoing circuit 1.So although when TRIAC 12 disconnects, some electric currents make some electric power be wasted via

resistor

14 and 16 by auxiliary winding 6(), the electric power of waste is more much smaller than the electric power of waste in circuit 1 in circuit 10.

TRIAC 12 plays the AC switch.When grid voltage rose to threshold voltage over TRIAC, TRIAC was switched on.TRIAC keeps on-state always until grid voltage drops to zero.When grid voltage dropped to (bearing) threshold voltage lower than TRIAC, TRIAC was switched on again, and keeps on-state until grid voltage rises to zero always.

Therefore, TRIAC 12 is all connected during the positive and negative half period of ac input voltage.But, on the zero crossing of each grid voltage, have a bit of time TRIAC to disconnect.The impact of this zero passage is described below with reference to Fig. 3.

Fig. 3 totally represents, illustrates the curve chart of analog result of the circuit of Fig. 2 with label 20.Curve Figure 20 comprises voltage curve 22 and current curve 24.Voltage curve 22 shows the voltage on the grid of TRIAC 12.Current curve 24 shows the electric current that flows through TRIAC 12.

On voltage and current curve 22 in being presented at Fig. 3 and 24 starting point, voltage is on 0 volt, and TRIAC is disconnected.Power supply 2 is AC power supplies, and is initial as shown in Figure 3, and voltage rises, but electric current 24 remains on 0 (because TRIAC remains disconnection).

When voltage 22 reached the threshold voltage of TRIAC 12, TRIAC was connected, and allows electric current pass through.But as shown in Figure 3, the connection of electric current is noisy, causes obvious current spike.

TRIAC keeps connecting (and allowing electric current pass through) until grid voltage drops to zero.Then TRIAC disconnects (not allowing electric current pass through) until grid voltage drops to the negative threshold voltage lower than TRIAC.Then, TRIAC is connected, and allows negative current pass through.And, as shown in Figure 3, when TRIAC is connected, large current spike appears.

Therefore, current spike appears on each zero crossing of grid voltage (that is on, each half period of ac input voltage).Noise in appearing at current signal 24, voltage signal 22 also comprises corresponding a series of spike.

Fig. 4 show with label 30 totally represent, a kind of measurement result that realizes of the circuit of Fig. 2.

Article one line of 30 has drawn the voltage at TRIAC 12 two ends as the function of time as a result.30 second line has drawn as the function of time the electric current that passes through TRIAC 12 as a result.The 3rd of 30 the line drawing as a result gone out the feature by the electric current of TRIAC 12.

At first, switch 3 is opened, so TRIAC 12 two ends do not have voltage, does not also have electric current to flow through TRIAC.

When switch 3 was closed, PTC resistor 4 was cold, and TRIAC is switched on.Therefore, as label 31 indications, the voltage at TRIAC two ends is similar to zero (because TRIAC is switched on) for some time.But, as high-visible in voltage measurements 31, on each zero crossing of AC power supplies, due to voltage spikes appears.Simultaneously, on the period that totally represents with label 33, the AC electric current flows through TRIAC 12(and therefore flows through auxiliary winding 6).And, current spike appears on zero crossing.

As mentioned above, as time goes by, the resistance of PTC resistor 14 reduces, thus the voltage drop on the grid of TRIAC 12 to the AC voltage source than small scale, TRIAC 12 is disconnected.

In the period that totally represents with label 32, TRIAC disconnects, and therefore can see at the two ends of TRIAC 12 whole AC voltage.Similarly, do not have electric current to pass through TRIAC (totally representing with label 34) within this time.

The 3rd of 30 the line is to pass through the feature of the electric current of TRIAC in switch 3 closures of opening a period of time as a result.Predict with reference to figure 3 described analog results as top, the current spike on each zero crossing of AC power supplies is high-visible.

The electric current and the due to voltage spikes that appear on each half period of AC power supplies are unacceptable in many cases.These spikes often are taken as electromagnetic interference (EMI).

Summary of the invention

The present invention attempts to solve at least some of the problem summarized above.

The invention provides comprise main winding, auxiliary winding and switching circuit exchange (AC) motor, wherein this switching circuit and this auxiliary winding serial form auxiliary winding-switching circuit pair, and this main winding assists winding-switching circuit in parallel with this, wherein this switching circuit comprises voltage divider, bidirectional triode thyristor and capacitor, wherein: this bidirectional triode thyristor and this auxiliary winding serial; This voltage divider comprises the first resistor and the second resistor; This first and second resistor is connected on the output of this voltage divider together; This first resistor is PTC resistor, and have with the first end of this auxiliary winding coupled (directly or other modes) and with the second end of the output coupling of this voltage divider; And this capacitor-coupled is between the gate input of this voltage divider output and this bidirectional triode thyristor.This bidirectional triode thyristor is TRIAC normally.

This bidirectional triode thyristor plays the AC switch.Electric current depends on that the voltage ground on the grid of this bidirectional triode thyristor flows through this auxiliary winding and this bidirectional triode thyristor.

In the use of motor, when this first resistor was relatively cold, AC power supplies generated the voltage that is enough to connect this bidirectional triode thyristor on the grid of this bidirectional triode thyristor.Therefore, allow electric current pass through this bidirectional triode thyristor, therefore by assisting winding.But when this first resistor was relatively warm, this bidirectional triode thyristor disconnected.When this bidirectional triode thyristor disconnects, the electric current that flows through this voltage divider less (due to relatively large resistance), the electric current that therefore flows through this auxiliary winding is less.

This motor is configured to be connected with interchange (AC) power supply usually, and wherein when connecting, this AC power assists winding-switching circuit in parallel with this main winding with this.This AC power supplies can be single-phase AC power supplies.This AC power supplies can be main supply.

This motor can comprise and being configured to this main winding and the switch that should auxiliary winding-switching circuit pair be coupled with AC power.In use, this AC power supplies assists winding-switching circuit in parallel with this main winding with being somebody's turn to do usually.

This motor can be compressor (for example, being used in refrigeration machine).The switch that this motor is connected with this AC power supplies can be the thermostat of refrigerator compressor.

This motor can further comprise the second PTC resistor that is coupling between this bidirectional triode thyristor and this auxiliary winding.This second PTC resistor can have the first end with the first end coupling of this auxiliary winding and this first resistor.

Description of drawings

With reference now to following schematic diagram, the present invention is described in more detail, in the accompanying drawings:

Fig. 1 is a kind of circuit diagram of electric system;

Fig. 2 is a kind of circuit diagram of electric system;

Fig. 3 shows the analog result of the circuit of Fig. 2;

Fig. 4 shows a kind of measurement result that realizes of the circuit of Fig. 2;

Fig. 5 is the circuit diagram according to the electric system of one aspect of the present invention;

Fig. 6 shows the schematic diagram for the circuit of the operation of the circuit of simulation drawing 5;

Fig. 7 shows the analog result of the circuit of Fig. 6;

Fig. 8 shows a part that is presented at the circuit in Fig. 6; And

Fig. 9 shows a kind of measurement result that realizes of the circuit of Fig. 6.

Embodiment

Fig. 5 be with label 40 totally represent, according to the circuit diagram of the electric system of one aspect of the present invention.Electric system 40 comprises AC power supplies 2, switch 3, main winding 4, auxiliary winding 6 and the PTC resistor 8 of foregoing circuit 1 and 10.Circuit 40 also comprises switching device 42.

Switching device 42 comprises bidirectional triode thyristor 44, the first resistor 46, the second resistor 48 and capacitor 52.Two-way three utmost point three utmost point thyristors 12 are TRIAC normally, and below be referred to as TRIAC.

The first resistor 46 and the second resistor 48 form the voltage divider between the second end that is connected to auxiliary winding 6 and power supply 2.The first resistor 46 is PTC resistors, and has the second end that the first end that is connected with auxiliary winding 6 is connected with first end with the first end of the second resistor 48 and capacitor 52.The second resistor 48 has the second end that is connected with the second end of voltage source 2.

Voltage divider is to be equipped with like this: along with the resistance increase of the first resistor 46, the voltage drop on the voltage divider mid point is to the low ratio of AC voltage source.Therefore, the voltage on that mid point raises along with temperature and descends.

Capacitor 52 is connected between the grid of the mid point of the voltage divider that is formed by the first device and the second resistor and TRIAC 44.

Fig. 6 shows the circuit that totally represents, is used for the operation of analog circuit 40 with label 60.Circuit 60 comprises AC power supplies 2, main winding 4, auxiliary winding 6, TRIAC 44,

resistor

8,46 and 48 and capacitor 52.Main winding 4 and auxiliary winding 6 are modeled into inductor.The function that is used for simulation TRIAC 44 based on transistorized circuit.Should comprise a npn transistor 62, a pnp transistor 64, the 2nd npn transistor 66 and the 2nd pnp transistor 68 based on transistorized circuit, below with reference to Fig. 8, it be made more detailed description.

Fig. 7 totally represents, illustrates the curve chart of analog result of the circuit of Fig. 5 with label 70.Curve Figure 70 comprises voltage curve 72 and current curve 74, and similar with above-mentioned curve Figure 20.Voltage curve 72 shows the voltage on the grid of TRIAC 44.Current curve 74 shows the electric current that flows through TRIAC 44.

With the same in Figure 20, on the voltage and current curve 72 in being presented at Fig. 7 and 74 starting point, voltage is on 0 volt, so TRIAC is disconnected.Power supply 2 is AC power supplies.When voltage 72 reached the threshold voltage of TRIAC 44, TRIAC was connected, and allows electric current pass through.As shown in Figure 7, a little jump is arranged in electric current 74.

As following with reference to figure 8 further as described in, on each zero crossing subsequently of voltage signal 72, the interaction between the transistor of capacitor 52 and TRIAC 44 has following effect: accelerate rate of change by the voltage of zero crossing with relative smooth manner.The voltage smooth change causes the electric current smooth change.So although voltage and

current waveform

72 and 74 is not fully sinusoidal, the clear spike of seeing has disappeared because of the effect of capacitor 52 in Fig. 2.

Fig. 8 totally represents, shows in simplified form the circuit above with reference to the part of the described circuit 60 of Fig. 6 with label 80.Circuit 80 comprises the first resistor 46, the second resistor 48, PTC resistor 8, capacitor 52, the first and second npn transistors 62 and the 68 and first and second pnp transistors 64 and 66.The many elements (especially main winding 4, auxiliary winding 6 and power supply 2) that are included in circuit 60 have for the sake of clarity been omitted.

Suppose voltage not to be put at first the voltage divider that is formed by

resistor

46 and 48, the grid voltage that makes TRIAC 44 is zero.In this stage, all

crystals pipe

62,64,66 and 68 all disconnects, and does not therefore have electric current to flow through TRIAC 44.

Now the voltage that is added on voltage divider two ends of dummy raises.When the voltage of the grid of TRIAC 44 rose to the threshold voltage of a npn transistor 62, that transistor was switched on.When transistor 62 was connected, the grid of a pnp transistor 64 was pulled to for zero (because it is connected with ground by a npn transistor 62).Therefore, a pnp transistor 64 is switched on, and make electric current flow through

transistor

64 and 62 to ground (also by auxiliary winding 6(be not presented in Fig. 8) and PTC resistor 8).

The electric current that flows through a pnp transistor 64 helps the TRIAC grid input side of capacitor 52 is charged.

The TRIAC gate electrode side of this capacitor must be in+0.7V (due to base-emitter voltage of transistor 62 and 64) to the voltage between-0.7V.But the voltage of this capacitor voltage divider side is all much bigger than this voltage on amplitude within the most of the time in the cycle of AC input signal.

Suppose that the AC input signal is the 50Hz signal, so, this capacitor was recharged within the most of the time of each 10ms half period of AC input, only discharged within the short time from zero crossing to the grid threshold voltage by TRIAC 44.

Just in time before zero crossing, the voltage on

resistor

46 and 48 mid points is remained on " high level " upper (that is to say, on 0.7V) by the electric charge on capacitor.Therefore, before the zero crossing of ac input voltage, the voltage on the grid of a npn transistor 62 remains on the base-emitter threshold value, makes TRIAC 44 keep conducting.

When input voltage (from AC power supplies 2) dropped to zero, a pnp transistor 64 disconnected, and was enough to because no longer include on the two ends of that transistorized base-emitter knot the voltage that retainer member is connected.The one npn transistor 62 also disconnects, because grid voltage no longer is enough to keep that device to be connected now.Voltage on the grid of TRIAC 44 drops to the base-emitter voltage of approximate-0.7V(transistor 66 from approximate+0.7V), connect transistor 66 at once after zero

crossing.Resistor

46 and 48 in name a person for a particular job and have same voltage drop, be then the negative charging period.

In this stage, auxiliary winding 6 is connected with ground with being connected via transistor 68, therefore makes electric current flow through auxiliary winding 6.

Again towards liter above freezing, before zero crossing, the 2nd npn transistor 68 remains on threshold voltage the voltage on pnp transistor 66 grids due to ac input voltage, makes TRIAC 44 keep conducting.

When input voltage rose to zero, the 2nd npn transistor 68 disconnected, and was enough to because no longer include on the two ends of that transistorized base-emitter knot the voltage that retainer member is connected.The 2nd pnp transistor 66 also disconnects, because grid voltage no longer is enough to keep that device to be connected now.

Voltage on the grid of TRIAC 44 rises to the base-emitter voltage of approximate+0.7V(transistor 62 from approximate-0.7V), and connect transistor 62 at once after zero crossing, this makes again a pnp transistor 64 connect.Then repeat above-mentioned circulation.

Fig. 9 show with label 90 totally represent, a kind of measurement result that realizes of the circuit of Fig. 6.

Article one line of 90 has drawn the voltage at TRIAC 44 two ends as the function of time as a result.90 second line has drawn as the function of time the electric current that passes through TRIAC 44 as a result.The 3rd of 90 the line drawing as a result gone out the feature by the electric current of TRIAC 44.

At first, switch 3 is opened, so TRIAC two ends do not have voltage, does not also have electric current to flow through TRIAC.

When switch 3 was closed, PTC resistor 46 was cold, and TRIAC is switched on.Therefore, as label 91 indications, the voltage at TRIAC two ends is similar to zero (because TRIAC is switched on) for some time.Note, from different in measurement result 30, formation voltage spike not.Simultaneously, on the period that totally represents with label 93, the AC electric current flows through TRIAC 44(and therefore flows through auxiliary winding 6).And, there is no current spike.

As mentioned above, as time goes by, the resistance of PTC resistor 46 reduces, so the voltage drop on the grid of TRIAC 44, and TRIAC 44 is disconnected.

In the period that totally represents with label 92, TRIAC disconnects, and therefore can see at the two ends of TRIAC 44 whole AC voltage.Similarly, do not have electric current to pass through TRIAC (totally representing with label 94) within this time.

The 3rd of 90 the line is to pass through the feature of the electric current of TRIAC in switch 3 closures as a result.Can find out, above-mentioned in result 30 apparent current spike disappeared from result 90.

The embodiment of the invention described above provides as just example.Those of ordinary skill in the art will recognize many modifications, the change that can not depart from scope of the present invention and make and substitute.Claims of the present invention are intended to contain as within the spirit and scope of the present invention all to be revised, changes and substitutes.

Claims

1. alternating current machine that comprises main winding, auxiliary winding and switching circuit, wherein this switching circuit and this auxiliary winding serial form auxiliary winding-switching circuit pair, and this main winding assists winding-switching circuit in parallel with this, wherein this switching circuit comprises voltage divider, bidirectional triode thyristor and capacitor, wherein:

This bidirectional triode thyristor and this auxiliary winding serial;

This voltage divider comprises the first resistor and the second resistor;

This first and second resistor is connected on the output of this voltage divider together;

This first resistor is PTC resistor, and have with the first end of this auxiliary winding coupled and with the second end of the output coupling of this voltage divider; And

This capacitor-coupled is between the gate input of this voltage divider output and this bidirectional triode thyristor.

2. motor as claimed in claim 1, wherein this motor is configured to be connected with AC power, wherein when connecting, this AC power with should assist winding-switching circuit in parallel with this main winding.

3. as claim 1 or motor claimed in claim 2, further comprise and be configured to this main winding and the switch that should auxiliary winding-switching circuit pair be coupled with AC power.

4. as any one described motor of claim 1 to 3, wherein this motor is compressor.

5. as the described motor of any one claim of front, further comprise the second PTC resistor that is coupling between this bidirectional triode thyristor and this auxiliary winding.

6. as the described motor of any one claim of front, wherein this bidirectional triode thyristor is TRIAC.