Patent ID: 12206348

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

According to the herein disclosed embodiments there is provided an electric machine drive arrangement for a heavy-duty vehicle aimed at mitigating the above disclosed issues.

FIG.2illustrates an electric machine drive arrangement200for a heavy-duty vehicle according to an embodiment.

The electric machine drive arrangement200comprises a motor drive system inverter120. The alternating current side of the motor drive system inverter120is arranged for interfacing with an electric machine110.

The electric machine drive arrangement200further comprises a brake arrangement220. The brake arrangement220comprises a braking resistor circuit222. The braking resistor circuit222is connectable to a control circuit224.

The electric machine drive arrangement200further comprises a rectifier arrangement210. The rectifier arrangement210is connected in parallel between the brake arrangement220and the motor drive system inverter120on the alternating current side of the motor drive system inverter120.

By introducing such a rectifier arrangement210in parallel with the motor drive system inverter120on the alternating current side of the motor drive system inverter120, and a braking resistor circuit222on the direct current side of the rectifier arrangement210, the above noted safety issue is mitigated. Further, the motor drive system inverter120does not need to be dimensioned for the brake power. Hence, the electric machine110may be overloaded (based on thermal overload capability) without impact on the dimensioning of the motor drive system inverter120. In particular, in some embodiments, the motor drive system inverter120is under-dimensioned with respect to a maximum brake power of the electric machine110. This implies that the maximum (instantaneous) dissipation effect is smaller than that of the electric machine110.

The electric angular speed and the alternating current (as measured by an alternating current measurement unit170) are, together with a direct current voltage (UDC), provided as input to an electric machine controller160. The electric machine controller160controls a switching pattern of inverter switches (not shown inFIG.2) provided in a motor drive system inverter120.

An energy storage system140is provided in parallel to the motor drive system inverter120. One purpose of the energy storage system140is to provide stable direct current voltage during switching. The energy storage system140is arranged to be further connected to one or more energy storage devices, such as batteries (not shown in figure).

A brake arrangement controller150is arranged to, in accordance with a duty cycle, control the switching pattern of the control circuit224(such as of a direct current chopper circuit and/or a thyristor switch provided in the control circuit224). The duty cycle of the switching determines the amount of power that is dissipated in the braking resistor circuit222.

By separating the braking resistor circuit222from the motor drive system inverter120and the energy storage system140, the safety issues of having the braking resistor circuit222in parallel with the energy storage system140is mitigated. In addition, since the motor drive system inverter120does not be dimensioned for the brake power, this enables to short term overload the electric machine110.

In some aspects, the motor drive system alternating current measurement is performed on the electric motor side of the rectifier arrangement210. That is, in some embodiments, the electric machine drive arrangement200further comprises an alternating current measurement unit170. The alternating current measurement unit170is arranged between the rectifier arrangement210and the electric machine110on the alternating current side of the rectifier arrangement210. By that, the torque control (or current control) of the motor drive system will still control the torque (or current) even when the braking resistor circuit222is conducting. Hence, the braking resistor circuit power load will be regarded as a load disturbance compensated by the electric machine controller160, maintaining the requested torque.

Reference is next made to the electric machine drive arrangement300ofFIG.3. The electric machine drive arrangement300shows one illustrative realization of the electric machine drive arrangement200.

In the realization exemplified by the electric machine drive arrangement300, the rectifier arrangement210is a three-phase rectifier composed of diodes212.

In the realization exemplified by the electric machine drive arrangement300, the braking resistor circuit222is a braking resistor. However, in other realizations of the electric machine drive arrangement200, the braking resistor circuit222is an electrical motor. The electrical motor is connectable to a mechanical brake circuit.

In the realization exemplified by the electric machine drive arrangement300, the control circuit224is a direct current chopper circuit. However, in other realizations of the electric machine drive arrangement200, the control circuit224is a thyristor switch. In further detail, when, for example, considering a motor drive arrangement100with an asynchronous electric machine110, the direct current chopper can be exchanged with a thyristor switch. The Thyristor will stop conducting when the current is zero. This is achieved by setting the reactive current in the electric machine controller160to zero and by that the rotor magnetic field will go to zero and the induced voltage will go to zero and by that the current will be zero.

Further, in the realization exemplified by the electric machine drive arrangement300, six switches122in addition to two capacitors124are provided in the motor drive system inverter120.

In this respect, the motor drive system inverter120can be realized in several ways. hereinFIG.3is illustrated a two-level voltage sources converter. However, the proposed electric machine drive arrangement is not limited to such a topology. The electric machine drive arrangement could be realized using any multi-level configuration and also two-phase and multi-phase electric machines110can be applied.

Further, in the realization exemplified by the electric machine drive arrangement300, the energy storage system140is provided as a battery another type of energy storage circuitry142.

FIG.4, andFIG.5provide examples of how the motor drive system inverter120power, the brake torque and direct current voltage of the motor drive system is affected when the power is shifted from the motor drive system inverter120to the brake arrangement220. InFIG.4and inFIG.5the control circuit224is activated at 10 seconds. As can be seen, activating the control circuit224causes minor disturbance on the brake torque as well as on the direct current voltage of the energy storage system140at the direct current side of the motor drive system inverter120. This minor disturbance is enabled by the herein disclosed electric machine drive arrangement200,300and by performing current measurements at the electric machine110.

Alternatives to having an electric machine drive arrangement200,300with a brake arrangement220comprising a braking resistor circuit222connectable to a control circuit224and a rectifier arrangement210connected in parallel between the brake arrangement220and the motor drive system inverter120on the alternating current side of the motor drive system inverter120will disclosed next.

In a first alternative electric machine drive arrangement, alternating current choppers are provided on the alternating current side of the motor drive system inverter120. One braking resistor per phase is then needed. In other words, the electric machine drive arrangement according to this first alternative is provided with separate choppers and braking resistors per phase. This requires all choppers and braking resistors to be coordinated in operation and also requires more components than the above disclosed electric machine drive arrangements200,300.

In a second alternative electric machine drive arrangement, a combination of circuit breakers and direct current choppers are provided in series on the direct current side of the motor drive system inverter120. Also in this second alternative, the electric machine drive arrangement is provided with separate choppers and braking resistors per phase. This requires all choppers and braking resistors to be coordinated in operation and also requires more components than the above disclosed electric machine drive arrangements200,300.

Accordingly, for both the first alternative electric machine drive arrangement and the second alternative, the motor drive system inverter120does not need to be dimensioned for the brake power. That is, the motor drive system inverter120does not need to be dimensioned with respect to the maximum brake power of the electric machine110.

In summary, the present inventive concept relates to an electric machine drive arrangement, where a rectifier arrangement210is configured in parallel with the motor drive system inverter120on the alternating current side of the motor drive system inverter120in the motor drive system, and where a brake arrangement220is arranged on the direct current side of the rectifier arrangement210. In this way the electric machine110may be overloaded (based on thermal overload capability) without impact on the dimensioning of the motor drive system inverter120. The motor drive system alternating current measurement is made on the electric motor side of the rectifier arrangement210. In this way the torque control (current control) of the motor drive system will still control the torque (current) even when the brake reactor is conducting. Hence, the brake resistor power load will just be a load disturbance compensated by the motor drive system controller, maintaining the requested torque.

The herein disclosed electric machine drive arrangements200,300are suitable for use in a vehicle600, such as a heavy-duty vehicle. The vehicle600might, by means of the electric machine110, be provided with electric traction.FIG.6schematically illustrates a vehicle600comprising an electric machine drive arrangement200,300as herein disclosed. In some embodiments, the vehicle600is a heavy-duty vehicle. In this respect, the present inventive concept is applicable to different types of heavy-duty vehicles600, such as, but not limited to, trucks, buses and construction equipment.

It is to be understood that the present inventive concept is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.