JP7206722B2 - motor generator controller - Google Patents

Description

The disclosed technology relates to a motor-generator control device that is suitable for hybrid vehicles and that can be used for both electric motors and generators.

Patent Literature 1 discloses a technique for solving the problem of the buck-boost converter. Specifically, the buck-boost converter has a problem that the cost is high and the system to which it is applied is enlarged. In addition, there is also a problem that efficiency is lowered due to switching loss and resistance loss.

Therefore, in the invention of Patent Document 1, a plurality of DC power sources are provided, and the DC voltage is switched stepwise by switching the connection of these power sources without burdening the switches. By doing so, the problems of buck-boost converters, such as system size increase and high cost, are resolved.

JP 2017-17825 A

When an electric motor is used as a drive source for a vehicle such as a hybrid vehicle, a wide range of driving force is required in terms of both torque and rotation speed. For example, at low speed such as starting, high torque is required because it is used for starting and starting the engine. On the other hand, when driving at high speed on level ground or downhill, high torque is not required, but high rotation is required.

Generally, in a hybrid vehicle, an electric motor is used not only as a drive source but also as a generator. That is, the electric motor recovers kinetic energy as electric energy by regenerating during braking (motor generator).

In order to secure high torque in such motor-generator motors (usually permanent magnet synchronous motors), the number of windings (stator coils) is generally relatively increased to generate strong magnetic force. is designed to

As the number of turns of the winding increases, the back electromotive force that hinders the rotation of the motor also increases. A high-voltage power supply can supply sufficient power to the motor even if the back electromotive force increases. However, in recent years, there has been a trend toward an increase in the number of hybrid vehicles that are driven using a low-voltage power source (for example, 60 V or less).

With such a low-voltage power supply, if the back electromotive force becomes large, the power becomes insufficient and it becomes difficult to drive at high rotation. Therefore, when a low-voltage power supply is used, control to weaken the back electromotive force, so-called flux-weakening control (also called field-weakening control), is performed over a wide range of rotation speeds in order to drive the motor at high speed. there is However, when performing flux-weakening control, it is necessary to supply a predetermined control current to the motor in order to weaken the back electromotive force. As a result, there is a problem that the drive efficiency and power generation efficiency of the motor are lowered.

A step-up/step-down converter may be used as a method of driving the motor at high speed without performing flux-weakening control. If a buck-boost converter is used, even a low-voltage power supply can be boosted to drive a motor at high speed. Also, the high voltage generated by the high-speed motor can be stepped down and recovered to the low-voltage power supply, that is, regenerated.

Regeneration occurs during braking when the vehicle slows down. Since the deceleration is normally performed when the automobile is traveling at high speed, the frequency of time is higher when the motor is running at high speed than when the motor is running at low speed. Therefore, in order to ensure high power generation efficiency, it is necessary to perform efficient step-down operation with the step-up/step-down converter when the number of revolutions of the motor is high.

However, the buck-boost converter has various problems that hinder the efficiency of the buck operation in relation to the buck operation, details of which will be described later. Therefore, when used in a motor-generator, the buck-boost converter not only has problems such as high cost and large size, but also has room for improvement in terms of buck operation.

Accordingly, an object of the disclosed technique is to realize, at a low cost, a motor-generator control device that has a compact structure and is capable of performing efficient step-down operation at the time of power generation.

The disclosed technology includes a motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups, an inverter driving and controlling the motor, and intervening between the inverter and a low-voltage power supply. The present invention relates to a motor-generator control device including a converter that performs step-up operation and step-down operation .

The motor-generator control device is mounted on a vehicle capable of traveling by being driven by the motor and traveling by being driven by the engine. A measuring unit that detects the operating state of the motor, and a control unit that outputs a signal to the inverter and the converter based on a signal input from the measuring unit to control the inverter and the converter.

The converter includes an arm connected to an upper wiring and a lower wiring for inputting and outputting to the high voltage side and the low voltage side of the inverter, respectively, and a first switching element connected in series from the high voltage side of the arm. and a second switching element, a first diode and a second diode connected in anti-parallel with each of the first switching element and the second switching element, and the first switching element and the second switching element in the arm and a coil installed in an intermediate wiring connected between and inputting and outputting to the high voltage side of the low voltage power supply. A switching element having a current capacity smaller than that of the first switching element is used as the second switching element, and a diode having a current capacity smaller than that of the second diode is used as the first diode. .

That is, in this motor-generator control device, a converter is provided between an inverter that drives and controls a so-called permanent magnet type motor and a low-voltage power supply for converting voltages input to and output from both. The converter has a first switching element, a second switching element, a first diode, a second diode, a coil, etc., like a conventional buck-boost converter.

Therefore, even if the rated voltage of the low-voltage power supply is low, by converting the voltage with a converter, the voltage of the low-voltage power supply can be boosted to drive the motor at a high voltage, or the high voltage obtained by the motor during regeneration can be used. It can be stepped down, adjusted to an appropriate voltage, and recovered to a low voltage power supply.

In the case of this converter, unlike the conventional buck-boost converter, a switching element having a smaller current capacity than the first switching element is used as the second switching element, and a switching element having a smaller current capacity than the first switching element is used as the first diode. A diode with a small current capacity is used.

In the case of a conventional buck-boost converter, one electric circuit performs both step-up and step-down operations. Therefore, a predetermined element such as a coil installed in an electric circuit must be designed according to the boosting operation that requires higher performance. As a result, from the viewpoint of step-down operation, the specifications become excessive, and not only are there disadvantages such as high cost and increased size, but there is also the problem of reduced efficiency in step-down operation.

In contrast, in this motor-generator control device, as described above, the current capacity of a predetermined switching element is reduced, and the electric circuit has a structure specialized for step-down operation. As a result, the efficiency of the step-down operation can be improved while simplifying the electric circuit. Since the converter can be made compact and the material cost can be reduced, a high-performance, small-sized control device can be realized at low cost.

The control unit may output a signal to the inverter when the motor is driven at a predetermined number of revolutions or higher, thereby executing flux-weakening control for supplying a flux-weakening current to the motor.

If the converter is specialized for step-down operation, the step-up performance of the converter is accordingly degraded. Therefore, it becomes difficult to drive the motor at high rotation speeds at which the back electromotive force generated by the motor increases. On the other hand, in this control device, flux-weakening control is performed when the motor is driven at a predetermined number of revolutions or more. If the flux-weakening control is performed, the back electromotive force of the motor can be weakened, so even if the boosting performance of the converter is degraded, it can be compensated for. Therefore, even if the converter is specialized for step-down operation, the motor can be driven at high speed.

The controller may control the flux-weakening current to increase as the rotation speed of the motor increases.

The higher the rotation speed of the motor, the greater the back electromotive force. On the other hand, if the flux-weakening current is increased, the back electromotive force can be weakened accordingly. Therefore, if the flux-weakening current is increased in accordance with an increase in the number of rotations of the motor, the motor can be efficiently driven at a high rotation speed.

The motor-generator controller can be further simplified from the structure described above.

For example, the motor-generator control device includes a motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups, a measuring unit for detecting the operating state of the motor, a low-voltage power supply connected to the inverter; a converter interposed between the inverter and the low-voltage power supply to convert voltages input to and output from both; and the measuring unit and a control unit that outputs a signal to the inverter and the converter based on a signal input from the inverter and the converter.

The converter is connected in series with an upper arm connected to an upper wiring for inputting/outputting to a high voltage side of the inverter, and connected to a lower wiring for inputting/outputting to a low voltage side of the inverter, connected in series with the upper arm. and a coil installed in an intermediate wiring connected between the upper arm and the lower arm and inputting/outputting to/from the high voltage side of the low voltage power supply. The upper arm is provided with one switching element and a first diode connected in anti-parallel with the switching element, and the lower arm is provided with only a second diode whose cathode side faces the high voltage side. It is

Then, the control unit outputs a signal to the converter to supply a flux-weakening current to the motor by outputting a signal to the inverter when the motor as an electric motor operates at a predetermined number of revolutions or more. When the motor operates as a generator, current is supplied to the low-voltage power supply while stepping down the voltage through the switching element and the coil.

That is, in the case of this motor-generator control device, the converter is dedicated to stepping down the voltage and does not perform the stepping up operation. Instead, the electrical circuit is more simplified, and the efficiency of step-down operation can be improved. Therefore, a more efficient and compact control device can be realized at a low cost.

The simplified motor-generator controller can also be realized in different constructions.

For example, the motor-generator control device includes a motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups, a measuring unit for detecting the operating state of the motor, a low-voltage power supply connected to the inverter; a converter interposed between the inverter and the low-voltage power supply to convert voltages input to and output from both; and the measuring unit and a control unit that outputs a signal to the inverter and the converter based on a signal input from the inverter and the converter.

The converter is connected to an upper wiring for inputting and outputting to the high voltage side of the inverter, and is connected in series with an upper arm having only one switching element with a collector side facing the high voltage side, and the upper arm. a lower arm connected to a lower wiring for inputting and outputting to the low voltage side of the inverter and having only one diode with the cathode side facing the high voltage side; the upper arm and the a coil installed in intermediate wiring connected between the lower arms and inputting/outputting to the high voltage side of the low voltage power supply; and a bypass arm having only one diode with the cathode side facing the high voltage side of the inverter.

Then, the control unit outputs a signal to the converter to supply current to the inverter through the detour arm when the motor as an electric motor operates at a predetermined number of revolutions or higher, and the motor as a generator supplies current to the inverter. During operation, current is supplied to the low-voltage power supply while stepping down through the switching element and the coil.

Also in the case of this motor-generator control device, the converter is dedicated to stepping down the voltage and does not perform the stepping up operation. The path through which the current for driving the motor flows is different from the motor-generator control device described above. That is, the current for driving the motor flows through the bypass arm to the upper wiring. Since the flow bypasses the coils, the loss can be reduced more than the motor-generator control device.

According to the disclosed technology, the circuit of the converter can be greatly simplified, and efficient step-down operation can be performed during power generation. Therefore, a compact and inexpensive motor-generator control device can be realized.

1 is a schematic diagram showing a main part of a vehicle to which disclosed technology is applied; FIG. It is a block diagram showing the main composition of a control device. It is a schematic diagram which shows the main structures of a motor. It is a schematic diagram which shows the winding structure of a motor. FIG. 4 is a diagram showing the operating range of the motor; FIG. 4 is a schematic diagram illustrating boosting operation in a general buck-boost converter; FIG. 2 is a schematic diagram explaining step-down operation in a general step-up/step-down converter; FIG. 2 is a schematic diagram showing the main configuration of the electric circuit of the converter in the embodiment; It is an example of control at the time of power running in the control device of the embodiment. It is an example of control at the time of regeneration in the control device of the embodiment. FIG. 10 is a schematic diagram showing a main configuration of an electric circuit of a converter in modification 1; FIG. 10 is a diagram showing a motor operating region in the control device of Modification 1; FIG. 10 is an example of control during power running in the control device of Modification 1; FIG. FIG. 11 is a schematic diagram showing a main configuration of an electric circuit of a converter in modification 2;

Embodiments of the disclosed technology will be described in detail below with reference to the drawings. However, the following description is essentially merely an example, and does not limit the present invention, its applications, or its uses.

<In-vehicle example>
FIG. 1 shows a vehicle 1 to which the technology disclosed is applied. The illustrated vehicle 1 is a so-called hybrid vehicle. A vehicle 1 is equipped with an engine 2, a motor generator 3, a low-voltage power supply 4, a PCM 5 (an example of a control unit), and the like. The motor generator 3 includes an inverter 10, a converter 20, a motor 30, and the like. A control device for controlling the motor generator 3 includes these devices 10, 20, and 30, the PCM 5, sensors 9a to 9e, etc., which will be described later.

The engine 2 is a known internal combustion engine that generates power for the vehicle 1 by burning fuel. The engine 2 is provided with a fuel tank, an intake/exhaust system, and the like (not shown since these are known). A crankshaft 2a of the engine 2 is connected in series with a rotary shaft 30a of a motor 30 via a clutch 6. As shown in FIG. A rotating shaft 30a of the motor 30 is connected to the driving wheels 1a of the vehicle 1 via the transmission 7, the differential gear 8, and the like. Transmission 7 also functions as a clutch.

By driving the engine 2 while the clutch 6 is engaged, the vehicle 1 can run by burning fuel, like a normal vehicle 1 . Further, by driving the motor 30 with the clutch 6 disengaged, the vehicle can be driven electrically. Furthermore, by driving the engine 2 and the motor 30 with the clutch 6 engaged, the vehicle 1 can run on both fuel combustion and electric power.

For example, when the engine 2 is stopped or temporarily stopped, the motor 30 is driven with the transmission 7 disengaged and the clutch 6 engaged. Thereby, the engine 2 can be started. By connecting the transmission 7 in this state, the output torque of the engine 2 can be assisted by the motor 30 when the vehicle 1 starts moving.

In addition, when the vehicle 1 is braked, the motor 30 can be rotated by the rotational force of the drive wheels 1a by disengaging the clutch 6, for example. Thereby, the motor 30 can be made to function as a generator, and the kinetic energy can be recovered to the low-voltage power supply 4 as electrical energy. This vehicle 1 is a so-called parallel hybrid vehicle.

The low voltage power supply 4 is a DC power supply. A specific example of the low-voltage power supply 4 is, for example, a rechargeable secondary battery. The low-voltage power supply 4 uses a relatively low voltage (rated voltage) of, for example, 48V, unlike a high-voltage power supply exceeding DC 60V that is common in hybrid vehicles and electric vehicles.

Low-voltage power supply 4 is electrically connected (hereinafter also simply referred to as connection) to motor 30 via inverter 10 and converter 20 . The inverter 10 is a device that converts DC power into AC power and outputs the AC power. The inverter 10 drives and controls the motor 30 .

Converter 20 is arranged to be interposed between inverter 10 and low voltage power supply 4 . Converter 20 may be arranged integrally with inverter 10 or low voltage power supply 4 . Converter 20 converts a DC voltage input to and output from both inverter 10 and low voltage power supply 4 . Converter 20 is a so-called DC/DC converter.

The PCM 5 (powertrain control module) is a device that comprehensively controls the operation of the vehicle 1, such as controlling the driving of the engine 2 and the motor 30, for example. The PCM 5 is a well-known microcomputer-based controller, and as shown in FIG. and an input/output bus 5c (I/O bus) for inputting/outputting signals.

The PCM 5 is connected with various sensors (an example of a measuring section) that detect the operating states of the engine 2 and the motor 30 . For example, a crank angle sensor 9b (a sensor attached to the engine 2 and measuring the rotation angle of the crankshaft 2a), an accelerator opening sensor 9c (attached to the accelerator pedal mechanism of the vehicle 1 and corresponding to the operation amount of the accelerator pedal). A sensor that measures the degree of opening of the accelerator), etc. are connected.

Furthermore, a motor sensor 9a (a sensor such as a resolver attached to the motor 30 and measuring the rotation angle of the rotating shaft 30a), a current sensor 9d (attached to the inverter 10 and measuring the magnitude of the current input/output to/from the inverter 10). measuring sensor), a voltage sensor 9e (a sensor attached to the inverter 10 and measuring the magnitude of the voltage output from the inverter 10), etc. are also connected to the PCM 5 . Detection signals output from these sensors are always input to the PCM 5 during operation of the vehicle 1 .

PCM 5 is also connected to inverter 10 and converter 20 . PCM 5 outputs control signals to inverter 10 and converter 20 to control inverter 10 and converter 20 based on detection signals input from sensors 9a to 9e described above. Thereby, the motor 30 is driven and controlled according to the driving state of the vehicle 1 .

(Motor 30, inverter 10, converter 20)
Motor 30, inverter 10, and converter 20 are schematically shown in FIG. 3A. The motor 30 of this embodiment is a so-called permanent magnet synchronous motor. The motor 30 has a stator 30b and a rotor 30c. The rotor 30c is provided integrally with the rotating shaft 30a. A plurality of permanent magnets 30d are arranged at equal intervals along the entire circumference of the rotor 30c. These permanent magnets 30d are arranged such that the N poles and S poles are alternately arranged in the circumferential direction and the radial direction, and constitute the magnetic poles of the rotor 30c.

The stator 30b has a substantially cylindrical shape and is arranged around the rotor 30c such that its inner peripheral surface faces the outer peripheral surface of the rotor 30c with a small gap therebetween. The stator 30b has a stator core 30e made of a magnetic material and a plurality of coils 30f. The stator core 30e has a plurality of slots arranged at regular intervals along its entire circumference. The coil 30f is constructed by winding a covered electric wire in a predetermined order through these slots.

Stator 30b is thereby provided with three different winding groups 50, consisting of a U-phase group, a V-phase group and a W-phase group, as shown in FIG. 3B. These winding groups 50 are connected to each other at a neutral point 51 (so-called Y-connection or star-connection).

Since the motor 30 is also used as a drive source for the vehicle 1, a wide range of driving force is required in terms of both torque and rotational speed. Therefore, the winding group 50 is designed to have a relatively large number of windings (high impedance) so as to generate a strong magnetic force so that a high torque can be output. Alternating currents in different phases are supplied from the inverter 10 to the winding groups 50 of each phase through respective input terminals.

(Motor operating range)
FIG. 4 illustrates the operating range of the motor 30. As shown in FIG. The vertical axis represents the level of the torque due to the motor output, and the horizontal axis represents the level of the rotation speed due to the motor output. The upper side of the horizontal axis is the operating range of the motor 30 as an electric motor, that is, the range during power running, and the lower side of the horizontal axis is the operating range of the motor 30 as the generator, that is, the range during regeneration.

As described above, in the case of this motor 30, the number of turns of the winding group 50 is designed to be relatively large so that high torque can be output. Therefore, the motor 30 can output a relatively high torque T (T') in the low rotation operating range. As a result, the maximum output torque of the motor 30 is kept substantially constant at the torque T in the low rotation region up to the rotation speed R1 at the voltage of the low voltage power supply 4 .

On the other hand, as the rotation speed of the motor 30 increases, the back electromotive force generated in the motor 30 also increases accordingly. As a result, the potential difference between the motor 30 and the voltage of the low-voltage power supply 4 becomes smaller. As a result, it becomes difficult to drive the motor 30 at high rotation, and the torque that can be output decreases as indicated by the virtual line L1 in FIG. In normal control with normal power supply, the motor 30 cannot be driven when the number of rotations exceeds a certain number of rotations (the number of rotations indicated by symbol R0 in FIG. 4).

Therefore, in the control device for the motor generator 3 (hereinafter also simply referred to as the control device), flux-weakening control is performed in order to drive the motor 30 even at a high rotational speed. Flux-weakening control is a known technique. In the flux-weakening control, a flux-weakening current (d-axis current) is supplied to each winding group 50 of the motor to adjust the voltage. By doing so, the back electromotive force is reduced. The flux-weakening current acts to weaken the magnetic flux generated by the rotating rotor 30c. By performing flux-weakening control, the motor 30 can be driven even at high rotation. As a result, the motor 30 can be driven even at high rotation, although the torque that can be output is reduced.

Then, normally, it is conceivable to install a step-up/step-down converter between the inverter 10 and the low-voltage power supply 4 . According to the buck-boost converter, as indicated by the virtual line L2 in FIG. 4, the voltage of the low-voltage power supply 4 is boosted over the entire high rotation side of the operating region of the motor 30, and the voltage is lowered due to the increase in back electromotive force. can be complemented. And it can be driven with relatively high torque even at high rotation.

Also, by installing a step-up/step-down converter, the high voltage generated by the motor 30 can be stepped down during regeneration, and the power generated by the motor 30 can be recovered to the low-voltage power supply 4 . Regeneration is performed during braking when the vehicle 1 decelerates. Therefore, when the motor 30 is operating at a high rotation speed, the frequency of regeneration in terms of time is higher than when the motor 30 is operating at a low rotation speed.

Therefore, in order to perform regeneration efficiently, it is important to ensure high power generation efficiency with the high-speed motor 30 . In order to ensure high power generation efficiency with the high-speed motor 30, it is necessary to perform efficient step-down operation with the step-up/step-down converter when the motor 30 is rotating at a high speed.

However, in the case of a step-up/step-down converter, a common electric circuit performs both step-up and step-down operations. Therefore, the inventors have found that there is a difference in efficiency between the step-up operation and the step-down operation, and that there is room for improvement. Based on this knowledge, in this control device, the electric circuit 20a of the converter 20 is improved to have a structure specialized for step-down operation rather than step-up operation (details of these will be described later).

Therefore, in this control device, first, the voltage of the low-voltage power supply 4 is stepped up by the converter 20 specialized for the step-down operation to compensate for the voltage drop due to the rise in the back electromotive force. As a result, the maximum output torque T (T') can be maintained up to a predetermined rotational speed R1 even if the rotational speed R1 is exceeded. Then, when the motor 30 is driven at a predetermined number of revolutions R2 or higher, in addition to boosting by the converter 20, further complementation by flux-weakening control is performed.

Since the converter 20 is specialized for step-down operation, even if the flux-weakening control is performed as in the step-up/step-down converter, it is not possible to compensate for the voltage drop due to the back electromotive force in the entire operating range of the motor 30. . In addition, the torque that can be output at high rotation also decreases. Therefore, in this control device, when the motor 30 reaches a predetermined rotation speed R3 (upper limit rotation speed R3), the motor 30 is stopped and the engine 2 is switched to independent driving.

Therefore, the operating range of the motor 30 during power running is limited to the upper limit rotation speed R3 in the rotation speed direction. The operation regions during power running are, in order from the low speed side, a normal drive region A1 in which the motor 30 is driven and controlled by the voltage of the low-voltage power supply 4 without boosting operation, and a first drive region A1 in which the boosting operation by the converter 20 is performed. It is divided into a complementary drive region A2 and a second complementary drive region A3 in which flux-weakening control is performed in addition to boosting operation by the converter 20 .

The normal drive region A1 is a region below the rotational speed R1, the first complementary driving region A2 is a region above the rotational speed R1 and below the rotational speed R2, and the second complementary driving region A3 is a region above the rotational speed R2. It is a region of number R3 or less.

The rotation speed R1 corresponds to, for example, the rotation speed at which the motor 30 cannot maintain the maximum output torque due to the back electromotive force at the voltage of the low-voltage power supply 4 . The rotation speed R2 varies depending on the maximum output of the low-voltage power supply 4 and the like. Therefore, the rotational speeds R1 and R2 are determined by the specifications of the control device such as the low-voltage power supply 4 and the motor 30. FIG.

The upper limit rotation speed R3 is also determined by the specifications of the control device. The upper limit rotation speed R3 is located on the low rotation side in the operating range of the vehicle 1 . For example, the upper limit rotation speed R3 can be located in a region on the low rotation side when the driving range of the vehicle 1 is roughly bisected in the direction of the rotation speed. Further, the upper limit rotation speed R3 can be located in the region on the lowest rotation side when the operating region of the vehicle 1 is divided into approximately three equal parts in the direction of the rotation speed. These rotational speeds are set in advance in the memory 5b.

On the other hand, the operating range of the motor 30 during regeneration is expanded to the high rotation side because the converter 20 is specialized for step-down operation. The operating region during regeneration is divided into a normal regeneration region A4 in which regeneration is performed based on the electromotive force generated by the motor 30 without step-down operation, and a complementary regeneration region A5 in which step-down operation is performed by the converter 20. . Also in the area on the high rotation side of the complementary regeneration area A5, flux-weakening control is performed in order to adjust the voltage during regeneration.

Therefore, when the vehicle 1 is running, the PCM 5 determines the driving state of the vehicle 1 based on detection signals input from sensors such as the crank angle sensor 9b, the accelerator opening sensor 9c, and the motor 30 sensor 9a. do. Based on the determination result, PCM 5 drives and controls engine 2 , outputs control signals to inverter 10 and converter 20 as necessary, and drives and controls motor 30 .

At that time, the PCM 5 switches the contents of control of the inverter 10 and the converter 20 according to each of the above-described regions based on the operating state of the motor 30 (for example, whether the number of revolutions is high or low, power or regeneration).

(Problem of buck-boost converter)
FIG. 5A and the like exemplify a case where a general buck-boost converter CON (chopper type) is installed between the inverter 10 and the low-voltage power supply 4 . The buck-boost converter CON has an electric circuit that performs a step-up operation and a step-down operation. FIG. 5A and the like show a simplified main electric circuit thereof.

Two switching elements 21a and 21b, two diodes 22a and 22b, and a coil 23 are provided in the electric circuit of the step-up/step-down converter CON. Specifically, an arm 25 (an upper arm 25U and a lower arm 25D) is attached to each of wirings (upper wiring 24U and lower wiring 24D) for inputting and outputting electricity to each of the high voltage side and the low voltage side of inverter 10. It is connected. The lower wiring 24D corresponds to a so-called reference potential, and is also connected to the low voltage side of the low voltage power supply 4. FIG.

Two switching elements (a first switching element 21a and a second switching element 21b) are serially connected to the arm 25 in order from the high voltage side. That is, the first switching element 21a is installed on the upper arm 25U, and the second switching element 21b is installed on the lower arm 25D.

These switching elements 21a and 21b are, for example, semiconductor switches such as MOS-FETs and IGBTs. The illustrated switching elements 21a, 21b are of the NPN type, with the collector located on the high voltage side and the emitter located on the low voltage side. Therefore, these switching elements 21a and 21b allow current to flow from the high voltage side to the low voltage side, but do not allow current to flow in the opposite direction.

Diodes (first diode 22a and second diode 22b) are connected in antiparallel to each of the first switching element 21a and the second switching element 21b. An intermediate wiring 26 is connected to the midpoint between the first switching element 21a and the second switching element 21b in the arm 25, in other words, the midpoint between the upper arm 25U and the lower arm 25D. The intermediate wiring 26 inputs and outputs electricity to the high voltage side of the low voltage power supply 4 . A coil 23 (reactor) is installed in the intermediate wiring 26 .

The diodes 22a and 22b connected in anti-parallel with the switching elements 21a and 21b are so-called free wheel diodes. The cathodes of these diodes 22a, 22b are located on the high voltage side and the anodes of these diodes 22a, 22b are located on the low voltage side. Therefore, these diodes 22a and 22b allow current to flow from the low voltage side to the high voltage side, but do not allow current to flow in the opposite direction.

When the switching elements 21a and 21b are turned off during energization, an electromotive force generated by the coil 23 momentarily applies a high voltage to the arm 25. FIG. Diodes 22a and 22b then pass current to protect switching elements 21a and 21b.

The step-up/step-down converter CON performs step-up operation using the second switching element 21b and the first diode 22a. That is, as shown in the left diagram of FIG. 5A, the second switching element 21b is turned on. As a result, current flows through the coil 23 and the second switching element 21b as indicated by the arrow Y1. Then, as shown in the right diagram of FIG. 5A, when the second switching element 21b is turned off, the electrical energy stored in the coil 23 is transferred to the high voltage side of the inverter 10 through the first diode 22a as indicated by the arrow line Y2. released to By continuously performing the ON/OFF operation of the second switching element 21b, the voltage output to the inverter 10 is boosted from the power supply voltage.

In order to perform the boosting operation efficiently, it is necessary to increase the inductance of the coil 23 and supply a large current to the coil 23 . As a result, the number of turns of the coil 23 increases and the size of the coil 23 increases. Moreover, since the temperature of the coil 23 becomes high when energized, it is necessary to take countermeasures against the temperature. Along with this, the buck-boost converter CON becomes costly, heavy, and large.

On the other hand, when the buck-boost converter CON performs a buck operation, the first switching element 21a and the second diode 22b are used. That is, as shown in the left diagram of FIG. 5B, the first switching element 21a is turned on. As a result, a current flows from the high voltage side of the inverter 10 through the first switching element 21a and the coil 23, as indicated by an arrow line Y3. At that time, the electric energy of the current is stored in the coil 23 and the midpoint side of the coil 23 becomes substantially the same potential as the high voltage side of the inverter 10 .

Then, as shown in the right diagram of FIG. 5B, when the first switching element 21a is turned off, as the coil 23 emits electric energy, as shown by the arrow line Y4, the second diode 22b and the coil 23 current flows. At that time, the midpoint side of the coil 23 has substantially the same potential as the low voltage side of the inverter 10 . By continuously performing the ON/OFF operation of the first switching element 21a, the voltage output as the power supply voltage is stepped down from the high voltage side of the inverter 10. FIG.

Since the current that flows when the first switching element 21a is turned on when the voltage is reduced flows into the low voltage power supply 4, the average value of the current flowing through the coil 23 is about half that when the voltage is increased. That is, the current flowing through the coil 23 is larger when the voltage is increased than when the voltage is decreased. Therefore, in the case of the buck-boost converter CON, the coil performance must be designed in accordance with the boost operation. As a result, the coil 23 becomes excessively large in terms of the step-down operation, resulting in a large magnetic loss. Therefore, the efficiency of the step-down operation is lowered.

Also, the first diode 22a does not function when the voltage is stepped down, but energy loss occurs due to its capacitance and leakage current. Therefore, this also reduces the efficiency of the step-down operation.

Further, a large current flows through the second switching element 21b during boosting. Therefore, a large current capacity that can withstand it is required. When the current capacity of the second switching element 21b is large, when the second switching element 21b is switched to perform synchronous rectification during step-down, it takes time to accumulate carriers, resulting in a slow switching speed. As a result, a large switching loss occurs when stepping down the voltage. Therefore, this also reduces the efficiency of the step-down operation.

(Electric circuit 20a of converter 20)
FIG. 6 shows an electric circuit 20a (only a main part) of the converter 20 of this embodiment. The electric circuit 20a has a structure specialized for step-down operation. The basic structure of the electric circuit 20a (for example, basic content and positional relationship of elements) is the same as the electric circuit of the conventional buck-boost converter CON described above.

For example, this electric circuit 20a is also provided with wiring (upper wiring 24U and lower wiring 24D), arm 25 (upper arm 25U and lower arm 25D), and intermediate wiring 26. FIG. These wirings are provided with two switching elements, two diodes, and a coil as elements (elements constituting the electric circuit 20a). Therefore, by using the same reference numerals for the configurations with the same contents, the explanation thereof will be omitted or simplified, and the different contents will be explained in detail.

The electric circuit 20a of the converter 20 is improved in structure so that the step-down operation can be performed more efficiently than the step-up operation on the premise that the drive of the motor 30 is limited to the low speed side of the operation range of the vehicle 1.

Specifically, a switching element (improved second switching element 21b') having a smaller current capacity than the first switching element 21a is used as the second switching element. A diode (improved first diode 22a') having a smaller current capacity than the second diode 22b is used as the first diode. As the coil, a coil (improved coil 23') that is smaller and has a higher density than the coil 23 of the buck-boost converter CON is used.

For example, the improved coil 23' has a small inductance and is miniaturized with a thin, short electric wire having a small current capacity. Along with this, heat generation during energization is also suppressed, so temperature countermeasures can be simplified, and the improved coil 23' can be densified. Therefore, the converter 20 can also be made compact. Since the magnetic loss that occurs when converter 20 performs the step-down operation is reduced, the efficiency of the step-down operation is improved.

Since the driving of the motor 30 is restricted to the low rotation speed side of the operating range of the vehicle 1, the boosting performance required of the converter 20 is lowered. As the improved first diode 22a', one having a small current capacity is used in accordance with the lowered boosting performance. As a result, the energy loss that occurs in the step-down operation is also reduced. Therefore, the efficiency of the step-down operation is further improved.

The improved second switching element 21b' also has a small current capacity in accordance with the lowered boosting performance. As a result, switching loss that may occur in step-down operation is also reduced. Therefore, the efficiency of the step-down operation is further improved.

(Example of control by control device)
FIG. 7 shows an example of control during power running in this control device. This control example shows a process in which the vehicle 1 starts running from a stopped state, gradually accelerates, and shifts to normal running.

When the operation of the vehicle 1 is started and the power is turned on, detection signals are constantly input to the PCM 5 from the sensors 9a to 9e and the like. The PCM 5 reads various information from these detection signals to determine the driving state of the vehicle 1 (step S1).

Based on these information, the PCM 5 determines whether the engine 2 is stopped (step S2). When determining that the engine 2 is stopped (including temporary stop), the PCM 5 disconnects the transmission 7, connects the clutch 6, and starts the engine 2 by the motor 30 (step S3). Since the motor 30 operates in the normal drive region A1, it can exhibit high torque with the voltage of the low voltage power supply 4. FIG. Therefore, the engine 2 can be stably started.

When the engine 2 starts, the vehicle 1 is driven by both the motor 30 and the engine 2 (step S4). Driving the motor 30 enables high-torque torque assist, so that the vehicle can start smoothly and stably.

Then, the PCM 5 determines whether or not the number of rotations of the motor 30 is equal to or higher than the number of rotations R1, that is, whether or not it has reached the first complementary driving area A2 (step S5). When determining that the rotation speed of the motor 30 has reached the rotation speed R1 or higher, the PCM 5 outputs a control signal to the converter 20 to start boosting operation (step S6). As a result, a voltage higher than the voltage of the low-voltage power supply 4 is supplied to the inverter 10, so that the motor 30 can perform torque assist while maintaining a high torque even if the rotational speed increases.

The PCM 5 then determines whether or not the number of rotations of the motor 30 is equal to or higher than the number of rotations R2, that is, whether or not the second complementary drive region A3 has been reached (step S7). When determining that the rotation speed of the motor 30 has reached the rotation speed R2 or higher, the PCM 5 outputs a control signal to the inverter 10 to start flux-weakening control (step S8). Specifically, the supply of the flux-weakening current to the motor 30 is started. As a result, the back electromotive force can be alleviated, and a rapid decrease in the output torque of the motor 30 can be avoided.

Then, the PCM 5 performs control so that the flux-weakening current increases as the rotation speed of the motor 30 increases (step S9). By doing so, the motor 30 can be driven with higher torque and up to a higher rotation speed, and the operating range of the motor 30 can be expanded to the high rotation side.

After that, the PCM 5 determines whether or not the rotation speed of the motor 30 has reached or exceeded the upper limit rotation speed R3 (step S10). When it is determined that the rotation speed of the motor 30 is equal to or higher than the upper limit rotation speed R3, the PCM 5 outputs a control signal to the converter 20 and the inverter 10 to stop driving the motor 30 and switch to independent driving of the engine 2 (step S11).

At the time of this switching, it is necessary to compensate for the decrease in the torque obtained by driving the motor 30 with the torque output by the engine 2 . At that time, a torque shock may occur. However, the amount of decrease in torque is relatively small, and the switching timing is relatively low rotation.

Therefore, the torque shock that may occur at that time is small, there is time to spare, and it can be easily suppressed. For example, instead of switching in a short period of time, a predetermined switching time is provided as indicated by the virtual line L3 in FIG. You may do so.

FIG. 8 shows an example of control when regeneration is performed while the vehicle 1 is running in this control device. The PCM 5 determines whether or not there is a regeneration request (step S21). For example, when the charging amount of the low-voltage power supply 4 is insufficient, the PCM 5 is instructed to request regeneration. When there is a regeneration request, the PCM 5 determines whether or not the vehicle 1 is braking, ie, decelerating, based on information from the sensors 9a to 9e (step S22). Then, when the PCM 5 determines that braking is being performed, it determines whether or not the rotation speed of the motor 30 is equal to or higher than the rotation speed R1 (step S23).

When it is determined that the number of rotations of the motor 30 is less than the number of rotations R1, that is, the normal regeneration region A4, the PCM 5 performs regeneration without stepping down the voltage. On the other hand, when it is determined that the rotation speed of the motor 30 is equal to or higher than the rotation speed R1, that is, it is in the complementary regeneration area A5, the PCM 5 outputs a control signal to the converter 20 to perform regeneration while stepping down the voltage. The PCM 5 also outputs a control signal to the inverter 10 as necessary to perform flux-weakening control.

According to this converter 20, during regeneration, the step-down operation can be performed with an efficiency equal to or higher than that in the case of using the step-up/step-down converter CON. Therefore, according to this control device, it is possible to effectively generate electric power while being compact and inexpensive.

<Modification 1>
As a modified example 1 of the control device described above, a control device in which the electric circuit 20a of the converter 20 is further simplified will be exemplified.

FIG. 9 shows the main part of the electric circuit 20Aa of the converter 20A. This converter 20A is different from the previous converter 20 in that it is dedicated to step-down. The basic structure of the electric circuit 20Aa is the same as the electric circuit 20a described above. Therefore, by using the same reference numerals for the configurations with the same contents, the explanation thereof will be omitted or simplified, and the different contents will be explained in detail.

The electric circuit 20Aa of the converter 20A is also provided with an upper wiring 24U, a lower wiring 24D, an upper arm 25U, a lower arm 25D, and an intermediate wiring 26. These elements include first switching elements 21a, An improved first diode 22a', a second diode 22b, and a step-down dedicated coil 23A, which will be described later, are provided. The improved second switching element 21b' does not exist in the electric circuit 20Aa of this converter 20A. This converter 20 is therefore even more simplified than the previous converter 20 .

Specifically, the upper arm 25U is provided with a first switching element 21a and an improved first diode 22a', similar to the electric circuit 20a. The lower arm 25D is provided with only one diode whose cathode side is directed to the high voltage side, that is, only the second diode 22b as an element.

As a result, although current can flow from the lower wiring 24D to the intermediate wiring 26, current cannot flow from the intermediate wiring 26 to the lower wiring 24D. Therefore, the converter 20A has a structure in which it can perform a step-down operation but cannot perform a step-up operation.

Since the step-up operation is not performed, the dedicated step-down coil 23A is made smaller and has a higher density than the improved coil 23'. The converter 20A is therefore even more compact. Further, since the magnetic loss generated in the step-down operation is further reduced, the efficiency of the step-down operation is further improved.

FIG. 10 illustrates the operating range of the motor 30 in the control device of Modification 1. As shown in FIG. The area during power running is reduced compared to the previous control device. The region during regeneration is the same as that of the previous control device.

Since the converter 20 does not boost the voltage, the PCM 5 immediately performs flux-weakening control when the rotational speed exceeds R1. When the rotation speed of the motor 30 reaches a predetermined rotation speed (upper limit rotation speed R3'), the driving of the motor 30 is stopped and the engine 2 is switched to independent driving. The upper limit rotation speed R3' here is smaller than the previous upper limit rotation speed R3.

Therefore, the operating region of the motor 30 during power running in this control device is divided into a normal driving region A1 and a second complementary driving region A3 in order from the low speed side. In the second complementary driving region A3 here, only flux-weakening control is performed.

On the other hand, the area during regeneration is the same as in the previous control device. That is, the operating range during regeneration is expanded to the high rotation side because converter 20A performs a step-down operation. As in the conventional case, the operating area during regeneration is divided into the normal regeneration area A4 and the complementary regeneration area A5.

FIG. 11 shows an example of control during power running in the control device of Modification 1. In FIG. Similar to FIG. 7, this control example also shows a control example of a process in which the vehicle 1 starts running from a stopped state and shifts to normal running. No boosting is performed in this controller. Except for this point, it is the same as the control example of the previous control device. Therefore, the control of the same content will be explained while omitting or simplifying.

The PCM 5 reads various information obtained from the sensors 9a to 9e (step S31). When it is determined that the engine 2 is stopped (Yes in step S32), the PCM 5 starts the engine 2 with the motor 30 (step S33). When the engine 2 starts, the PCM 5 starts the vehicle 1 by driving both the motor 30 and the engine 2 (step S34).

The PCM 5 determines whether or not the rotation speed of the motor 30 is equal to or higher than the rotation speed R1, that is, whether or not it has reached the second complementary drive region A3 (step S35). Then, when it is determined that the rotation speed of the motor 30 is equal to or higher than the rotation speed R1, the PCM 5 outputs a control signal to the inverter 10 to start the flux-weakening control. is increased (steps S36, S37). After that, when the PCM 5 determines that the rotation speed of the motor 30 has reached or exceeded the upper limit rotation speed R3' (Yes in step S38), it outputs a control signal to the converter 20 and the inverter 10 to stop driving the motor 30. The engine 2 is switched to independent drive (step S39).

The control during regeneration is the same as the previous control device. That is, the control example shown in FIG. 8 can also be applied to the control device of the first modification. Therefore, even in the control device of Modification 1, during regeneration, the step-down operation can be performed with an efficiency equal to or higher than that in the case of using the step-up/step-down converter CON.

<Modification 2>
As in Modification 1, a control device in which electric circuit 20a of converter 20 is simplified is illustrated. FIG. 12 shows a main part of the electric circuit 20Ba of the converter 20B. This converter 20B is also the same as the first modification in that it is dedicated to step-down, but the structure of the electric circuit 20Ba is different.

In the electric circuit 20Ba of this converter 20B, there are no components corresponding to the first diode 22a and the second switching element 21b in the conventional buck-boost converter CON. On the other hand, a detour arm 27 with one diode (third diode 28) is newly provided.

Specifically, only the first switching element 21a is installed on the upper arm 25U as an element. Since the first diode 22a does not exist, there is no energy loss due to the first diode 22a when stepping down the voltage. Therefore, the efficiency of step-down operation can be improved. Since there is no first diode 22a, the electric circuit 20Ba can be simplified and made more compact and low cost.

Only the second diode 22b is installed as an element on the lower arm 25D. Since the second switching element 21b does not exist, the electric circuit 20Ba can be simplified and made more compact and low cost.

A dedicated step-down coil 23A is installed in the intermediate wiring 26, as in the first modification. Therefore, the converter 20B becomes compact. The efficiency of the step-down operation is improved because the magnetic loss generated in the step-down operation is greatly reduced.

A detour arm 27 is connected between the upper wiring 24U and the intermediate wiring 26 so as to be parallel to the first switching element 21a and the coil 23A. This detour arm 27 is provided with only a diode whose cathode side is directed to the high voltage side of the inverter 10, that is, only a third diode 28 as an element.

The operating range of the motor 30 in the control device of Modification 2 is the same as that of Modification 1. FIG. However, in the control device of Modification 2, the path through which the current flows when the motor 30 is driven is different from that in Modification 1. FIG.

12, the current flowing from the high voltage side of the low voltage power supply 4 when the motor 30 is driven flows through the detour arm 27 to the upper wiring 24U. Since it flows around the coil 23A, the loss can be reduced.

The control in the control device of Modification 2 is the same as that of the control device of Modification 1. FIG. That is, the control examples shown in FIGS. 8 and 11 can also be applied to the control device of the second modification. Therefore, even in the control device of Modification 2, during regeneration, the step-down operation can be performed with an efficiency equal to or higher than that in the case of using the step-up/step-down converter CON.

It should be noted that the motor-generator control device according to the technology disclosed is not limited to the above-described embodiments, and includes various other configurations.

In the control device of Modification 1, the improved first diode 22a' may also be omitted from the electric circuit 20Aa of the converter 20A, and the converter 20A may be completely dedicated to step-down. In this case, the motor 30 cannot be driven. The driving source of the vehicle 1 is only the engine 2 . Therefore, the motor 30 is specialized for regeneration, and the motor-generator becomes a generator.

In the control device of Modified Example 2, a switching element may be installed so as to be anti-parallel with the second diode 22b and the third diode 28, and synchronous rectification processing may be performed. By doing so, the forward voltage loss of these diodes 22b and 28 can be reduced. In this case, since the power applied to these switching elements is very small compared to the first switching element 21a and the second switching element 21b of the buck-boost converter CON, there is an advantage that small-sized elements can be used.

1 vehicle 2 engine 3 motor generator 4 low voltage power supply 5 PCM (an example of a control unit)
10 Inverter 20 Converter 20a Electric circuit 21a' Improved first switching element 21b' Improved second switching element 22a First diode 22b Second diode 23' Improved coil 25U Upper arm 25D Lower arm 26 Intermediate wiring 30 Motor

Claims (4)

a motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups; an inverter for driving and controlling the motor; A control device for a motor generator including a converter that performs step-down operation ,
mounted on a vehicle capable of running by driving the motor and running by the engine,
a measurement unit that detects the operating state of the motor;
a control unit for controlling by outputting signals to the inverter and the converter based on the signal input from the measurement unit;
with
The converter is
an arm connected to an upper wiring and a lower wiring for inputting and outputting to each of the high voltage side and the low voltage side of the inverter;
a first switching element and a second switching element connected in series in order from the high voltage side of the arm;
a first diode and a second diode connected in anti-parallel to each of the first switching element and the second switching element;
a coil installed in an intermediate wiring connected between the first switching element and the second switching element in the arm and inputting/outputting to/from the high voltage side of the low voltage power supply;
has
A switching element having a current capacity smaller than that of the first switching element is used as the second switching element, and a diode having a current capacity smaller than that of the second diode is used as the first diode ,
The control unit outputs a signal to the inverter and the converter, thereby executing flux weakening control for supplying a flux weakening current to the motor when the motor as an electric motor operates at a predetermined number of revolutions or more, and When the rotational speed reaches the upper limit higher than the predetermined rotational speed, the motor is stopped and driven by the engine, and when the motor operates as a generator, the voltage is stepped down through the first switching element and the coil. a control device for a motor generator that supplies current to the low voltage power supply while In the motor-generator control device according to claim 1,
A control device for a motor-generator, wherein the control unit performs control such that the flux-weakening current increases as the rotation speed of the motor increases. A motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups, an inverter for driving and controlling the motor, and a step-down operation interposed between the inverter and a low-voltage power supply. A motor-generator control device comprising a converter that performs
mounted on a vehicle capable of running by driving the motor and running by the engine,
a measurement unit that detects the operating state of the motor;
a control unit for controlling by outputting signals to the inverter and the converter based on the signal input from the measurement unit;
with
The converter is
an upper arm connected to an upper wiring that inputs and outputs to a high voltage side of the inverter;
a lower arm connected in series with the upper arm and connected to a lower wiring that inputs and outputs to the low voltage side of the inverter;
a coil installed in an intermediate wiring connected between the upper arm and the lower arm and inputting/outputting to the high voltage side of the low voltage power supply;
has
The upper arm is provided with one switching element and a first diode connected in anti-parallel with the switching element, and the lower arm is provided with only a second diode whose cathode side faces the high voltage side. being
The control unit outputs a signal to the inverter and the converter, thereby executing flux weakening control for supplying a flux weakening current to the motor when the motor as an electric motor operates at a predetermined number of revolutions or more, and When the upper limit number of revolutions is higher than the predetermined number of revolutions, the motor stops driving and is driven by the engine. Motor-generator controller that supplies current to a low-voltage power supply. A motor having a rotor provided with permanent magnets and a stator provided with a plurality of different winding groups, an inverter for driving and controlling the motor, and a step-down operation interposed between the inverter and a low-voltage power supply. A motor-generator control device comprising a converter that performs
mounted on a vehicle capable of running by driving the motor and running by the engine,
a measurement unit that detects the operating state of the motor;
a control unit for controlling by outputting signals to the inverter and the converter based on the signal input from the measurement unit;
with
The converter is
an upper arm connected to the upper wiring for inputting and outputting to the high voltage side of the inverter and having only one switching element with the collector side facing the high voltage side;
a lower arm connected in series with the upper arm and connected to the lower wiring for inputting/outputting to the low voltage side of the inverter, and having only one diode with the cathode side directed toward the high voltage side; ,
a coil installed in an intermediate wiring connected between the upper arm and the lower arm and inputting/outputting to the high voltage side of the low voltage power supply;
a detour arm connected to the upper wiring and the intermediate wiring so as to be in parallel with the switching element and the coil, and having only one diode with the cathode side directed toward the high voltage side of the inverter; ,
has
The control unit outputs a signal to the inverter and the converter so that when the motor as an electric motor operates at a predetermined number of revolutions or higher, the motor is weakened while supplying current to the inverter through the detour arm. While performing flux-weakening control for supplying a magnetic flux current, when the rotational speed reaches an upper limit higher than the predetermined rotational speed, the motor is stopped and driven by the engine, and the motor operates as a generator. A motor-generator control device that supplies current to the low-voltage power supply while stepping down the voltage through the switching element and the coil.

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