JP2017510238A - Voltage converter for electric machines installed in vehicles - Google Patents

Abstract

By a switch configured to convert an input voltage to an output voltage, a control unit for sending a control signal to the switch to convert an input voltage to an output voltage, and a control unit for controlling the switch At least one operating unit (UP) of the switch for adapting the transmitted control signal, and to allow signal transmission between the control unit and the operating unit (UP) through a magnetic circuit; An isolation transformer (14) having at least one primary winding and at least one secondary winding arranged between the control unit and the functional element (16) of the operating unit (UP), the primary A voltage converter for an electric machine mounted in a vehicle, in which the winding circuit and the secondary winding circuit are connected to the same voltage ground.

Description

  The present invention relates to a voltage converter for an electric machine mounted in a vehicle. Specifically, the present invention relates to a DC / AC voltage converter for supplying power to an electric motor of an air conditioning compressor mounted in a vehicle. The present invention also relates to a compressor for cooling liquid mounted in a vehicle.

  In particular, an air conditioning compressor mounted in a vehicle is known for cooling a vehicle interior. FR2814783A1 describes an example of such a compressor that includes a coolant compression mechanism driven by a dedicated electric motor and is powered by a voltage converter. The compression mechanism, the electric motor and the voltage converter are in a single housing and are optionally arranged in a specific housing of the housing.

  Typically, the voltage converter includes a switch connected to a high voltage battery that powers the electric motor. Due to the need for safety, the voltage converter is isolated from other parts of the vehicle, in particular the low voltage circuit of the vehicle, in particular to avoid user electrocution. U.S. Pat. No. 6,137,705 describes a voltage converter insulated from the vehicle low voltage circuit by an isolation element between the voltage control unit and the vehicle low voltage circuit. It concerns safety insulation.

  The transducer also includes insulation between the switch operating unit and the transducer control unit. In this case, it relates to functional insulation. Isolation between the switch operating unit and the converter control unit is performed by the gate oxide of the field effect transistor. However, gate oxides have parasitic capacitances that cause currents that can be dangerous associated with sudden voltage fluctuations. Gate oxides are also brittle, which poses a risk of loss of insulation. Furthermore, the insulation voltage is limited.

FR2814783A1 U.S. Pat.No. 6,137,705

  Thus, the problem is posed to improve the insulation between the switch operating unit and the converter control unit.

In order to solve this problem, the present invention provides:
-A switch configured to convert input voltage to output voltage;
A control unit for sending a control signal to the switch so as to convert an input voltage into an output voltage;
-At least one operating unit of the switch for adapting the control signal sent by the control unit to control the switch;
-At least one primary winding and at least one second arranged between the control unit and the functional element of the operating unit so as to allow signal transmission between the control unit and the operating unit through a magnetic circuit; The present invention relates to a voltage converter for an electric machine mounted in a vehicle, including an insulating transformer having a secondary winding.

  By means of a transformer, galvanic isolation separates the control unit from the operating unit of the switch. The transformer is more reliable in its electrical isolation function than the gate oxide of field effect transistors disclosed in the prior art. Galvanic isolation has a very low parasitic capacitance between windings. In that case, the impedance is even higher and does not facilitate current passage. This current can be detrimental to electromagnetic compatibility or to the component itself. Potential obstacles within the operating unit are therefore reduced and the robustness of the operating unit is increased. In particular, the operating unit in the converter according to the invention has a low latch-up effect.

  By means of the transformer, the transmission of signals, in particular voltage signals, between the control unit and the operating unit can be ensured even if the control and operating unit has very different ground levels.

  The isolation transformer can increase the tolerance of the control signal. Signal control and variation can be even faster, which improves switching losses.

  The voltage converter may be a converter that converts an AC voltage to a DC voltage or vice versa, or may be a converter that converts a DC voltage to a DC voltage. In particular, the converter may allow to power the electrical machine and / or recover the voltage delivered by the electrical machine.

  According to one embodiment, the switch is disposed on one or more arms, the arms including at least two switches in series separated by a midpoint.

  According to one embodiment, the transformer includes a primary winding coupled to the control unit and a secondary winding for each transistor in the arm. In this way, a single transformer can be used for all the switches of the arm, thereby reducing the external dimensions of the voltage converter.

  According to one embodiment, the primary winding circuit and the secondary winding circuit are coupled to the same voltage ground. This has the advantage of simplifying the converter circuit.

  According to one embodiment, the ground is common to the ground to which the end of the arm is connected. Thereby, in addition to simplification of the circuit of the converter, it is possible to use only one power supply for all operating units of the converter.

  The present invention also relates to a compressor for a coolant circuit including a fluid compression mechanism connected to an electric motor, the compressor according to the invention for supplying power to the compression mechanism, the motor and the electric motor. And a housing for storing the container.

  The invention will be better understood with reference to the drawings.

FIG. 3 shows a circuit including a voltage converter according to the invention. FIG. 2 is a diagram showing an example of a switch operation unit that can be used in the converter of FIG. FIG. 3 is a diagram showing an example of an isolation transformer that can be used in the operation unit of FIG.

  The circuit of FIG. 1 includes a DC / AC voltage converter or inverter 10 that converts a DC input voltage sent by the power supply 12 to an AC output voltage to power the electric motor M.

  In particular, the motor M is connected to a coolant compression mechanism (not shown). The compression mechanism, motor M and voltage converter 10 form a compressor for the electrically controlled coolant circuit. Such a compressor is, for example, a passenger compartment air conditioning compressor mounted in a vehicle.

  The voltage converter 10 includes switches A1, A2, B1, B2, C1, C2 configured to convert a DC input voltage to an AC output voltage. In particular, the switches are arranged on arms A, B, C. Each arm includes two switches in series separated by a midpoint. In the embodiment considered, the voltage converter 10 includes three arms A, B, C to power a motor M that is three-phase. Each arm has one end connected to the anode of the power supply 12 and the other end connected to the ground GND HT of the power supply 12.

  The switches A1, A2, B1, B2, C1, C2, and C3 may be field effect transistors such as MOS or IGBT. These switches include freewheeling diodes in parallel with the transistors. This diode may be specific to the transistor in particular.

  The converter 10 sends a signal to the switches A1, A2, B1, B2, C1, C2, C3, and controls the opening and closing of the switch so as to convert the DC input voltage into the AC output voltage. Including a control unit UC for controlling

  The converter 10 includes an operating unit UP for adapting the control signal sent by the control unit UC, in particular its voltage. The operating unit UP adapts the control signal for the operation of the switch.

  Typically, the controller 15 controls the converter 10 in communication with the control unit UC in the vehicle.

  The power source 12 is a high voltage power source having a voltage of 250V to 450V, for example. Other electrical components of the vehicle can be powered by a low voltage power supply 13 having, for example, a voltage between 9V and 16V and a corresponding ground GND BT. For example, the low voltage power supply 13 supplies power to the controller 15.

  FIG. 2 shows an example of the operation unit UP. The operating unit UP includes an insulating transformer 14 arranged between the control unit UC and the functional element 16 of the operating unit UP. These functional elements 16 adapt the control signals sent by the control unit UC to operate the respective switches and are known per se.

  The operating unit UP receives as input the signal sent out by the control unit UC. The operating unit UP may include a signal processing unit 9 for adapting the signal sent by the control unit UC for transmission via the isolation transformer 14. For example, the processing unit 9 converts the signal into a frequency modulation signal. An amplifier Amp may be present at the output of the processing unit 9 to amplify the signal sent to the isolation transformer 14. In addition, the operating unit UP may include a processing unit 11 at the output of the isolation transformer 14 in order to adapt the signal originating from the transformer 14 to the functional element 16. For example, the processing unit 11 demodulates a signal derived from the transformer 14. By means of the isolation transformer 14, galvanic insulation is obtained between the operating unit UP and the control unit UC, while enabling transmission of signals between the control unit UC and the operating unit UP. In contrast to the prior art where isolation is provided by field effect transistor gates, the isolation transformer 14 operates the switch faster without risking loss of isolation and minimizes the common mode current that causes this degradation. Makes it possible to suppress. The gate oxide can break and cause poor insulation, and the transformer 14 is more robust because it is better insulated by the structure. Thus, the transformer 14 provides more robust insulation.

  The transformer 14 can withstand a grounding difference between the control unit UC and the operation unit UP. In other words, the transformer 14 can reliably transmit a signal, particularly a voltage signal, between the control unit UC and the operation unit UP even if the control unit UC and the operation unit UP have different ground levels. This is especially true for the control units UP of the switches A1, B1, C1, which are connected to the anode of the power supply 12 by one of its terminals, ie the switches A1, B1, C1, located above the arms A, B, C. obtain.

  In FIG. 2, only the elements necessary for understanding the present invention are displayed. The operating unit UP can include other components. In particular, the operating unit UP is similar to that shown in FIG. 2 and is parallel but arranged in reverse, i.e. the processing unit 9 is on the functional element 16 side and the processing unit 11 is the operating unit. Another circuit including the processing unit 9, the isolation transformer 14, and the processing unit 11 on the input side of the UP may be included. This second circuit has a function similar to that shown in FIG. 2 and allows the transmission of an insulation signal between the operating unit UP and the control unit UC.

  FIG. 3 shows an embodiment of the isolation transformer 14. The isolation transformer 14 includes a primary winding 141 and a secondary winding 142 wound around each branch of the magnetic circuit 140 that guides magnetic flux. Primary winding 141 generates a magnetic flux around circuit 140 to induce a voltage in secondary winding 142.

  Therefore, the secondary winding 142 sends a signal generated from the control unit UC to the operation function elements dedicated to the transistors of the arms A, B, and C. In one embodiment, the isolation transformer 14 includes a second secondary winding. The second secondary winding sends a control signal to the functional element dedicated to the other transistor of arms A, B, and C. In this way, only one isolation transformer 14 can be used for both transistors of the arm, which reduces the external dimensions of the voltage converter 10.

  The electrical circuit 143 coupled to the primary winding 141 and the electrical circuit 144 coupled to the secondary winding 142 can be coupled to the same voltage ground. This may be especially true for the switches A2, B2, C2 of the lower arms A, B, C, ie the switches A2, B2, C2 connected to the ground of the power supply 12 by one of its terminals.

  In particular, the grounding of the electric circuits 143 and 144 connected to the primary winding 141 and the secondary winding 142 is common to the ground GND HT to which the ends of the arms A, B, and C are connected. In this way, only one power supply can be used for all operating units UP of the voltage converter 10, and the converter is simplified for that. In particular, the converter is simplified in that it is not necessary to provide electrical insulation between the operating unit UP and its power supply.

  In order to provide safety isolation between high and low voltage, the insulating wall 20 is designed to prevent the high voltage circuit and low voltage so as to avoid endangering the user due to the propagation of high voltage across the low voltage circuit. It may be provided between the voltage circuit. For example, an insulating communication element 19 such as an optical coupler may be disposed between the controller 15 and the control unit UC of the converter 10 in order to ensure communication through the insulating wall 20. An isolated power supply 17 such as a flyback converter can be used to power components located on the high voltage side with the voltage generated from the low voltage power supply 13.

  The voltage converter 10 is particularly suitable for being incorporated into a compressor for a coolant circuit mounted in a vehicle.

  The invention is not limited to the described embodiments. In particular, the transducer may include several arms different from three.

9 Processing unit
10 Voltage converter
11 Processing unit
12 Power supply
13 Low voltage power supply
14 Isolation transformer
15 Controller
16 functional elements
17 Insulated power supply
19 Insulated communication element
141 Primary winding
142 Secondary winding
143 Primary winding circuit
144 Secondary winding circuit
A, B, C arm
A1, A2, B1, B2, C1, C2, C3 switch
GND HT Ground
M Electric machine, electric motor
UC control unit
UP operation unit

Claims (5)

-Switches (A1, A2, B1, B2, C1, C2, C3) configured to convert input voltage to output voltage;
A control unit (UC) for sending a control signal to the switches (A1, A2, B1, B2, C1, C2, C3) to convert the input voltage into the output voltage;
-At least one operating unit (UP) of the switch for adapting the control signal sent by the control unit to control the switch;
-Between the control unit (UC) and the functional element (16) of the operation unit (UP) so as to enable signal transmission between the control unit (UC) and the operation unit (UP) through a magnetic circuit; An isolation transformer (14) having at least one primary winding (141) and at least one secondary winding (142) disposed therebetween,
The primary winding (141) circuit (143) and the secondary winding (142) circuit (144) are coupled to the same voltage ground (GND HT),
A voltage converter (10) for an electric machine (M) mounted in a vehicle.   The converter according to claim 1, wherein the switch is arranged on one or more arms (A, B, C), the arm comprising at least two switches in series separated by a midpoint.   The converter according to claim 2, wherein the transformer (14) includes a primary winding (141) coupled to a control unit (UC) and a secondary winding (142) for each transistor of the arm. .   4. The converter according to claim 2, wherein the ground (GND HT) is common to the ground to which an end of the arm (A, B, C) is connected.   A compressor for a coolant circuit including a fluid compression mechanism connected to an electric motor (M), wherein the compressor, the motor (M), and the electric motor (M) for supplying power 5. A compressor, further comprising a housing that houses the converter (10) according to any one of 4 above.

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