Device for driving electric vehicles / means of transport according to the principle of the series-wound / double-wound motor, characterized in that the commutation / polarity reversal of the current is carried out by electronic semiconductor switches / circuits.

Abstract

Device for driving electric vehicles / means of transport according to the principle of the series-wound / double-wound motor, characterized in that the commutation / reversal of the current is carried out by electronic semiconductor switches / circuits.

Description

[0001] The invention relates to a device for driving electric vehicles / means of transport according to the principle of the series-wound / compound-wound motor, wherein the amount of the armature current is equal or at least partially equal or proportional to the excitation current, characterized in that the commutation / polarity reversal of the current is not carried out electromechanically by brushes and split collectors, but by electronic semiconductor switches / circuits.

[0002] There are various drive concepts / motors for electrically powered vehicles with permanently excited motors or externally excited synchronous motors, which are used to drive electrically powered vehicles. The electrical power loss PV of the copper windings in permanent or externally excited motors is the maximum possible torque due to PV- I 2 , M(I)~I, PV ~ M 2and the power loss PV increases quadratically with the torque, thereby severely limiting it.

[0003] In the series motor, the torque dependence M(n)- U / n 2 ( Fig. 4), and because of M~I 2 the dependence of the power loss PV- M. Thus, the power loss PV in the series-wound motor is only linearly dependent on the torque.

[0004] This means that a higher torque is available from the motor of a comparable size, with the same heating due to electrical power loss. The series-wound motor has a higher torque than BLDC or synchronous motors ( Fig. 4) the advantage of a higher starting torque M at lower speed n. ( Fig. 8) shows that for the current ratio IE / IA=1 or IA=IE, at constant power loss Pvmax for the torque M, there is a maximum. Conversely, this means that with M as the parameter, the power loss has a minimum at IE=IA. This speaks in favor of the series-wound motor or its principle IA =IE or IA-IE, especially for vehicles that require high torque. According to ( Fig. 3) the efficiency characteristic curve over the torque η(M) is: η=11+R*Cr2ω η≠f(M)

[0005] Without speed-dependent power losses such as rolling friction and magnetic power losses, the efficiency η is constant over the torque M and is not a function of the torque. With magnetic power losses and rolling friction approximately represented with mgv as linear to the speed, the following applies: ηseries.=11+R*Cr2ω+R*Cr*mgvω*M+mgvM

[0006] With: cr 2 =I N 2 / MN

[0007] Here, the efficiency η is nearly constant at higher torque M, as the two last terms in the denominator become smaller with increasing M. The efficiency then depends exclusively on the speed and some machine constants. Because n ~ 1 / √M, a speed control is shown in Fig. 28 to make the speed n independent of the torque M. η=11+M*R*CBLDC2ω η=f(M)

[0008] In comparison, the efficiency of state-of-the-art electric drives depends on speed and torque and drops significantly at higher loads. Fig. 1) With magnetic losses applies to the BLDC motor. ηBLDC=11+R*CBIDC2*(M+mgv)2ω∗M+mgvM

[0009] With: C BLDC =I N / M N

[0010] In characteristic curves Fig. 9 and Fig. 10 shows the efficiency as a function of the torque with ω = 125 and ω = 62.5, for a fictitious engine with P N =200 KW, UN=400V ω N =250 corresponds to 100kmh and η=95% losses per ½ copper and ½ magnetic at I N . It is in Fig. 9 and Fig. 10 shows that the efficiency is below M N The torque is higher in a BLDC motor than in a series-wound motor, which is why it's possible to incorporate an additional armature direct current or shunt winding, based on the compound-wound motor principle. The torque depends on the current and input voltage as follows: Pmech=ω1∗M1=U1*I1(loss-free) if: M2=m*M1 then: I2=√m*I1 n2=n1 / √m so that n2=n1 must be: U2=√m*U1

[0011] Then: Pmech2=ω1*M1*(m)=(√m*U1)*(√m*I1)

[0012] If M changes by a factor of m, this is carried by the current by a factor of √m and by the input voltage by a factor of √m, which does not contribute to the power loss as long as the speed does not change.

[0013] Until now, the commutation of the armature current has been a problem in series-wound motors, as brushes and split collectors and the well-known brush sparking caused heavy wear, which required a high level of maintenance.

[0014] (Fig. Z1) shows a schematic circuit diagram of the series-wound motor. According to the invention, this is achieved through commutation using semiconductor / switching circuits and switches that are now very well-known in power electronics, such as MOSFETs or IGBTs.

[0015] This eliminates the electromechanical polarity reversal and its disadvantages such as brush sparks, high wear and maintenance costs.

[0016] The drive system proposed here is also applicable for multi-pole machines and excitation windings with the resulting lower speeds and higher torque.

[0017] Because of the ( Fig. 6) shown, which enable a smoother and more even driving style, an application for transport vehicles or for passenger transport such as public buses is advantageous.

[0018] In general, the high torque characteristics are also suitable for accelerating large masses such as trucks when starting / accelerating and when driving on inclines with limited engine size.

[0019] The series-wound motor is also characterized by high power density and less vibration. Fig. 9 and Fig. 10 better efficiency even for cars at low speeds in, for example, city traffic with frequent acceleration because a higher torque is required.

[0020] However, at very low load torque and high input voltage, such as when driving downhill, the speed can become very high. It must be considered whether an additional constant armature current / armature magnetic field, as in the compound wound motor principle, should be activated for such cases, or whether other speed-limiting measures should be implemented. Energy recovery during vehicle braking is also possible through an explicit armature current component independent of the excitation current, with the motor acting as a power generator.

[0021] A further consideration of the dependence of torque and speed at limited power is interesting for the application of the motor in e-bikes.

[0022] If: ω * M=P elek =const.

[0023] Then : M2=M1*m I2=√m*I1 ω2'=ω1 / √m U2=Pelek / √m*I1 U2=U1 / √m (M*m)*(ω / m)=Pelek.=const. M=Pelect / ω

[0024] With power loss, a characteristic curve results Fig. 11 M=Pelek.−mgv*ωω+R*Cr2

[0025] This can be interesting for e-mountain bikes to provide additional torque when riding uphill, where the power is limited to 250 W (up to the maximum possible power loss). To achieve this, the controller must limit the input power and the maximum current. See Fig. Z10.

[0026] In Fig. Figure 11 shows the torque as a function of angular velocity. The input power is limited to 278 W with an efficiency of 90%. The torque increases with decreasing speed.

[0027] Such a hyperbolic characteristic curve can also be achieved by varying the armature current and excitation current. Fig. Z5 shows an example circuit for separate adjustment of the armature current and excitation current. This allows for an increase / variation of the speed when the field is weakened by the excitation current. In combination with the variation of the armature current, different M(n) variants can be controlled. This also applies to a hyperbola with constant power according to Fig. 11.

[0028] In the circuit shown in Fig. Z2, polarity reversal is achieved by an H-bridge, and current collection is achieved by brushes and closed, uninterrupted collectors. The timing of the electronic polarity reversal is determined by the signal from the angle sensor connected to the rotor. This prevents brush sparking or excessive wear.

[0029] Such current collectors are also used today in separately excited synchronous motors. In these cases, the brushes only need to be replaced every approximately 100,000 kilometers, and maintenance costs are low due to their easy installation. Fig. Z3 shows how an H-bridge circuit can be constructed using MOSFETs and the armature circuit.

[0030] It is also possible to transfer the armature current to the rotor side by magnetic induction, whereby the polarity reversal on the rotor side is carried out by electronics as a controlled rectification with additional transmission of the necessary control signals.

[0031] Fig.Z4 Here, a fixed pulse and pulse ratio are present on the stator side. The proportionality between excitation current and armature current is determined by the dependence of IA on the electrical voltage across the bridge circuit.

[0032] Another circuit variant is shown in Fig. Z5, where the armature current and the excitation current are each fed via separate power supplies and are not directly connected in series. Nevertheless, the armature current is dependent on the excitation current, as this is measured electrically, and the armature current is adjusted to the excitation current via a control loop. The polarity reversal / commutation is performed in an H-bridge circuit, as shown in Fig. Z5.

[0033] Fig.Z6 shows a compact circuit with a combined buck converter from the power supply with simultaneous commutation circuit.

[0034] Fig.Z7 However, commutation of the excitation circuit is also possible, whereby the amount of the armature current is fully or partially proportional to the excitation current.

[0035] Fig. Z.8 shows a block diagram for speed control, so that the speed and rpm n are independent of the torque M. Here, the speed dependence on the torque is counteracted by controlling UEin. Fig. Z9 shows the injection of an additional armature current IA0 or armature field for speed limitation. The speed is limited according to the principle of a compound-wound motor and for generator operation during braking or driving on a downhill slope.

[0036] Fig. Figure 7 shows the speed characteristic curve n(M) for readjustment via U1 to Umax and the curve with further increasing load torque as well as the curve of Pmech and the curve of efficiency η and the electrical power loss PV.

[0037] Fig. 8 shows the comparison of power loss of BLDC and series motor Fig. 1 BLDC characteristic curve Fig. 2 Characteristic curve series connection n(M) and I(M) without losses Fig. 3 Characteristic curve series connection Pmech(M); I(M), Pv (M), efficiency η(M) Fig. 4 M(n) , I(n) diagram for the series motor.

[0038] In M(n) the electrical power loss and a mechanical friction load and magnetic losses are incorporated as linear to the speed. M=U2*Cr2(ω+R*Cr)2 Fig. 5 when increasing from M1 to Mb by increasing U2 to U3, n changes in the course of a(t) Fig. 7 M as a function of the ratio IA to IE with Pv as parameter results in the maximum of M at IA=IE.

[0039] Furthermore, various combinations of the circuits shown are possible, and not all of them can be shown here. Vehicles are understood here to be means of transport regardless of the medium of travel, such as air, water, or land-based vehicles. Identifier: LE Inductance of the excitation winding RE Ohmic resistance of the excitation winding LA Inductance of the armature winding RA Ohmic resistance of the armature winding S1z, S2 two-part collectors with brushes IE excitation current IA Armature current UEin Motor input voltage S1,S2 uninterrupted collectors with brushes U(φ) signal from the rotor angle / position sensor φ(t) angle of rotation of the rotor Utakt(φ), Ust(φ) Control voltage depending on the angle of rotation TR transformer Ubat battery voltage v speed CR, C BLDC Motor constants M torque ω angular velocity η efficiency PV power loss Pmech mechanical power R Ohmic resistance U...Ui motor voltage IN rated current UN nominal voltage PN rated power MN Nominal torque ω N Angular velocity at rated speed Efficiency with electrical losses 1) Series connection m. Pv=(RE+RA)*I2 with: I 2 = C1 2 * M Pv=c12*RG∗M 2) Pmech=ω*M 3) BLDC: Pv=c52*RE*M2 4) η=PabPzu=PmechPmech+Pv 5) Efficiency of series-wound motor η=PabPzu=PmechPmech+Pv with (Eq. 1) and (Eq. 2) η=11+R*cr2ωη≠f(M) Efficiency BLDC motor η=11+M*R*CBLDC2ωη=f(M) (Eq. 3) in (Eq. 5) Efficiency of series-wound motor with magnetic losses η=PmechPelek Pelek=ω*M+R*Cr2∗(M+mgv)+ω*mgv=U*I ηseries=1ω*M+R∗Cr2∗(M+mgv)+ω*mgvω*M η=11+R*cr2ω+R*cr2mgvω*M+mgvM BLDC efficiency with magnetic losses Pelek=ω*M+R∗Cr2∗(M+mgv)2+ω*mgv=U*I ηBLDC=11+R*Cr2(M+mgv)2ω*M+mgvM

Claims

[1] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that the commutation / reversal of the current is carried out by electronic semiconductor switches / circuits. [2] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 1), the excitation current is at least partially equal to or proportional to the armature current or is a mathematical function of IE = f(IA) and also allows a variation of the excitation current via a further parameter independent of the armature current IA, [3] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 1) and 2), the armature current can be transferred to the rotor side by magnetic induction. [4] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 3), a combination of controlled rectification / inverter for commutation can take place on the rotor side. [5] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 1), separate current feeds can be provided for the armature current and the excitation current in accordance with Fig.Z5. [6] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that the polarity reversal according to claim 1) and 2) can also take place in the excitation circuit. [7] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized bythat a control and stabilization of the speed in a control loop can take place via the input voltage as the output variable of the control loop according to Fig.Z8. [8] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that a regulation or limitation of the engine power can take place according to Fig.Z 10. [9] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 1), a shunt winding may be present [10] Device for driving electric vehicles / means of transport according to the principle of the series-wound / combined-wound motor characterized by that, according to claim 1), the motor can also be designed as an external rotor motor.

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