JP2018183012A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a power transmission efficiency when performing wireless electric power transmission.SOLUTION: A power conversion device 1 according to the present invention comprises: a boosting DC-DC converter 11 connected between a battery 2 and a primary side DC capacitor 12; a primary side single phase inverter 13 connected between the primary side DC capacitor 12 and a primary resonance circuit 14; a secondary side single phase inverter 24 connected between a secondary resonance circuit 21 and a secondary side DC capacitor 25; a three-phase inverter 26 connected between the secondary side DC capacitor 25 and an electric motor 3; a boosting DC-DC converter 35 connected between the secondary side DC capacitor 25 and a capacitor 37; and a secondary side microcomputer 43 for controlling the boosting DC-DC converter 35 so that a current Ic such that a voltage E2 follows a voltage command E2flows through the capacitor 37.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device that performs wireless power transfer between a primary side connected to a battery and a secondary side connected to a motor.

  In recent years, wireless power transmission, which transmits power wirelessly without using a cable, has attracted attention. As one application example of wireless power transmission, there is a system in which a drive source (motor) is disposed on the wheel side of a vehicle, wirelessly transmits power from the vehicle body side to the wheel side, and drives the drive source. Such a system is referred to as a wireless in-wheel motor drive system (see Non-Patent Documents 1 and 2).

  FIG. 7 is a diagram showing a configuration example of a power conversion device 1A applied to wireless power transmission as described above. Power conversion device 1A shown in FIG. 7 performs wireless power transmission between the primary side provided with battery 2 and the secondary side provided with motor 3 to convert DC power of battery 2 into three-phase AC power. To supply the electric motor 3.

  Power converter 1A shown in FIG. 7 includes a step-up / step-down DC-DC converter 11, a primary DC capacitor 12, a primary single-phase inverter 13, a primary resonant circuit 14, a primary radio 17, and a primary side. The microcomputer 18A, the secondary resonance circuit 21, the secondary single-phase inverter 24, the secondary DC capacitor 25, the three-phase inverter 26, the current detector 27, the voltage detector 28, and the speed detector 29 , A phase detector 41, a secondary side wireless device 42, and a secondary side microcomputer 43A. The step-up / step-down DC-DC converter 11, the primary side DC capacitor 12, the primary single phase inverter 13, the primary resonant circuit 14, the primary radio 17, and the primary microcomputer 18A are provided on the primary side. In addition, the secondary resonance circuit 21, secondary side single phase inverter 24, secondary side DC capacitor 25, three phase inverter 26, current detector 27, voltage detector 28, speed detector 29, phase detector 41, secondary The side wireless device 42 and the secondary side microcomputer 43A are provided on the secondary side.

  A buck-boost DC-DC converter 11 is connected between the battery 2 and the primary DC capacitor 12. Further, a primary side single-phase inverter 13 is connected between the primary side DC capacitor 12 and the primary resonant circuit 14. The primary resonant circuit 14 is configured by connecting a capacitor 15 and an inductor 16 in series, and has a resonant frequency f.

  The primary side single-phase inverter 13 is composed of switching elements Q1 to Q4 in which diodes are respectively connected in antiparallel. Switching element Q1 and switching element Q2 are connected in series, and switching element Q3 and switching element Q4 are connected in series. A series body composed of switching elements Q1 and Q2 and a series body composed of switching elements Q3 and Q4 are connected in parallel to primary side DC capacitor 12. Further, a connection point between the switching element Q1 and the switching element Q2 and a connection point between the switching element Q3 and the switching element Q4 are connected to the primary resonance circuit 14. The primary side single-phase inverter 13 converts the voltage E1 of the primary side DC capacitor 12 into a voltage V1 having the same frequency as the resonant frequency f of the primary resonant circuit 14 and outputs the voltage V1 to the primary resonant circuit 14.

  The primary side wireless device 17 performs wireless communication with the secondary side wireless device 42 according to the control of the primary side microcomputer 18A.

The primary microcomputer 18A receives a torque command T ^* for instructing the torque of the motor 3 and outputs gate signals for controlling on / off of switching elements constituting the step-up / step-down DC-DC converter 11 and the primary single-phase inverter 13. Do. In addition, the primary side microcomputer 18A causes the primary side wireless device 17 to transmit the torque command T ^* to the secondary side wireless device 42.

  The secondary side single phase inverter 24 is connected between the secondary resonant circuit 21 and the secondary side DC capacitor 25. The secondary resonant circuit 21 is configured by connecting an inductor 22 and a capacitor 23 in series. The secondary resonant circuit 21 has the same resonant frequency f as the primary resonant circuit 14 and is magnetically coupled to the primary resonant circuit 14.

  The secondary side single-phase inverter 24 is composed of switching elements Q5 to Q8 in which diodes are respectively connected in antiparallel. Switching element Q5 and switching element Q6 are connected in series, and switching element Q7 and switching element Q8 are connected in series. A series body composed of switching elements Q5 and Q6 and a series body composed of switching elements Q7 and Q8 are connected in parallel to secondary side DC capacitor 25. Further, a connection point between the switching element Q5 and the switching element Q6 and a connection point between the switching element Q7 and the switching element Q8 are connected to the secondary resonance circuit 21. The secondary side single phase inverter 24 converts the voltage E2 of the secondary side DC capacitor 25 into a voltage V2 having the same frequency as the resonant frequency f of the secondary resonant circuit 21 and outputs the voltage V2 to the secondary resonant circuit 21.

  A three-phase inverter 26 is connected between the secondary side DC capacitor 25 and the motor 3. The three-phase inverter 26 converts the voltage E2 of the secondary side DC capacitor 25 into a three-phase AC voltage and outputs it to the motor 3.

  The current detector 27 detects the current I2 flowing through the secondary side single-phase inverter 24 and outputs the detection result to the phase detector 41. The voltage detector 28 detects the voltage E2 of the secondary DC capacitor 25 and outputs the detection result to the secondary microcomputer 43A. The speed detector 29 detects the speed ω of the motor 3 and outputs the detection result to the secondary microcomputer 43A.

  The secondary side wireless device 42 performs wireless communication with the primary side wireless device 17 according to the control of the secondary side microcomputer 43A.

The phase detector 41 detects the phase of the current I2 detected by the current detector 27, and outputs the detection result to the secondary microcomputer 43A. The secondary side microcomputer 43A includes a voltage E2 detected by the voltage detector 28, a speed ω detected by the speed detector 29, a phase of the current I2 detected by the phase detector 41, and a secondary side wireless device Based on the torque command T ^* received via 42, a gate signal for controlling on / off of the switching elements constituting the secondary side single phase inverter 24 and the three phase inverter 26 is generated.

  FIG. 8 is a diagram showing a waveform example of gate signals G5 and G7, current I2 and current V2 of switching elements Q5 and Q7 according to voltage E2 described in Non-Patent Document 1. As shown in FIG. Although not shown, the gate signals of the switching elements Q6 and Q8 are signals obtained by inverting the gate signals G5 and G7, respectively.

The current I2 is expressed by the following equation (1) using the mutual inductance M of the primary resonant circuit 14 and the secondary resonant circuit 21, the resonant frequency f and the voltage V1.

  In the equation (1), for example, when the voltage V1 is fixed, the current I2 has a fixed value. When the motor 3 is in the power running state and the voltage E2 is smaller than the predetermined value E2 ', the gate signals of the switching elements Q5 and Q7 are output so that the voltage V2 having the same phase as the current I2 is output from the secondary side single phase inverter 24. G5 and G7 are controlled. By outputting the voltage V2 in phase with the current I2, the secondary side DC capacitor 25 is charged, and the voltage E2 rises. Then, when the voltage E2 exceeds the predetermined value E2 ', the gate signals G5 and G7 are controlled such that the voltage V2 output from the secondary side single phase inverter 24 becomes zero. When the voltage V2 becomes 0, charging of the secondary side DC capacitor 25 is stopped.

  When the motor 3 is in the regenerative state, the voltage E2 rises. Then, when the voltage E2 exceeds the predetermined value E2 ′ ′, the gate signals G5 and G7 are controlled such that the voltage V2 in reverse phase to the current I2 is output from the secondary side single phase inverter 24. By outputting the voltage V2 in reverse phase to the current I2, the secondary side DC capacitor 25 is discharged, and the voltage E2 decreases. Thus, the voltage E2 of the secondary side DC capacitor 25 is controlled within a predetermined range.

  FIG. 9 is a diagram showing a waveform example of gate signals G5 and G7, current I2 and current V2 in the phase shift method of shifting the phases of gate signals G5 and G7 described in Non-Patent Document 2. In FIG.

  In the phase shift method described in Non-Patent Document 2, as shown in FIG. 9, the rising of the gate signal G5 is advanced by Ts / 4 (Ts is the time of one cycle of the current I2) by αTs / 4. In this timing, the rising of the gate signal G7 is delayed from Ts / 4 by αTs / 4. However, −1 ≦ α ≦ 1.

  By shifting the rising edges of the gate signals G5 and G7, the voltage V2 has a pulse width of αTs / 2 when the current I2 is positive and the magnitude becomes E2 with a pulse width of αTs / 2 when α ≧ 0, and the voltage V2 is negative. Is a pulse width of αTs / 2 and the magnitude is -E2. Therefore, the phase of voltage V2 coincides with the phase of current I2, and secondary side DC capacitor 25 is charged.

  When α <0, when the current I2 is positive, the voltage V2 has a pulse width of αTs / 2 and the magnitude is −E2, and when the current I2 is negative, the voltage V2 has a pulse width of αTs / 2 It becomes E2. Therefore, the voltage V2 has a waveform in which the phase of the current I2 is inverted, and the secondary DC capacitor 25 is discharged. As described above, the pulse width of the voltage V2 occupying one cycle of the current I2 has a value corresponding to α. Hereinafter, α is referred to as a pulse width ratio.

Motoki Sato, Giuseppe Guidi, Takehiro Imura, Hiroshi Fujimoto, “Model for Loss Calculation Wireless In-Wheel Motor Concept Based on Magnetic Resonant Coupling”, IEEE Workshop on Control and Modeling for Power Electronics COMPEL 2016, 2016 Motoki Sato, Giuseppe Guidi, Takehiro Imura, Hiroshi Fujimoto, “Experimental Verification for Wireless In-Wheel Motor using Synchronous Rectification with Magnetic Resonance Coupling”, International Electric Vehicle Technology Conference & Automotive Power Electronics Japan 2016, 2016

  By applying the method described in Non-Patent Documents 1 and 2 to the power conversion device 1A shown in FIG. 7, power can be bidirectionally supplied between the battery 2 and the motor 3. However, in the power conversion device 1A shown in FIG. 7, the step-up / step-down DC-DC converter 11, the primary side single-phase inverter 13, and the primary resonance circuit 14 are always performed when performing power transmission between the battery 2 and the motor 3. Since a plurality of power converters and resonance circuits such as the secondary resonance circuit 21, the secondary side single-phase inverter 24, and the three-phase inverter 26 are involved, there is a problem that the transmission efficiency of power is deteriorated.

  An object of the present invention is to provide a power conversion device capable of solving the above-mentioned problems and improving power transmission efficiency when performing wireless power transmission between the primary side and the secondary side. .

In order to solve the above problems, a power conversion device according to the present invention is a power conversion device that performs wireless power transfer between a primary side provided with a battery and a secondary side provided with a motor, DC-DC capacitor, primary resonance circuit having a resonance frequency f, buck-boost DC-DC converter connected between the battery and the primary-side DC capacitor, primary-side DC capacitor, and primary-resonance circuit And a primary side single-phase inverter connected to the first resonant circuit to output a voltage V1 having the same frequency as the resonant frequency f to the primary resonant circuit, and having the same resonant frequency f as the primary resonant circuit; Connected between the secondary resonant circuit coupled to the secondary side, the secondary side DC capacitor, the capacitor, the secondary resonant circuit and the secondary side DC capacitor, and having the same resonant frequency f A secondary side single-phase inverter for outputting a voltage V2 of a frequency to the secondary resonant circuit, a three-phase inverter connected between the secondary side DC capacitor and the motor, the secondary side DC capacitor, and A step-up type DC-DC converter connected between the capacitor, and a current Ic that causes the voltage E2 to follow the voltage command E2 ^* that instructs the voltage E2 of the secondary side DC capacitor to flow in the capacitor And a secondary side control unit that controls the step-up DC-DC converter.

  ADVANTAGE OF THE INVENTION According to the power converter device which concerns on this invention, the improvement of the transmission efficiency of the electric power at the time of performing wireless power transmission between a primary side and a secondary side can be aimed at.

It is a figure which shows the structural example of a power converter device by one Embodiment of this invention. It is a figure which shows the structural example of the duty calculation block with which the secondary side microcomputer shown in FIG. 1 is equipped. It is a figure which shows the structural example of the electric power instruction | command calculation block with which the secondary side microcomputer shown in FIG. 1 is equipped. It is a figure which shows the example of a waveform of voltage command E3 ^* . It is a figure which shows the voltage command and pulse width ratio calculation block with which the secondary side microcomputer shown in FIG. 1 is equipped. FIG. 6 is a view showing a waveform example of a voltage command V1 ^* and a pulse width ratio α calculated by a voltage command / pulse width ratio calculation block shown in FIG. 5; It is a figure which shows the structural example of the conventional power converter device. It is a figure which shows an example of the waveform of the electric current I2, gate signal G5, G7, and the voltage V2 in the conventional power converter device. It is a figure which shows another example of the waveform of the electric current I2, gate signal G5, G7, and the voltage V2 in the conventional power converter device.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a diagram showing a configuration example of a power conversion device 1 according to an embodiment of the present invention. In FIG. 1, the same components as in FIG. 7 will be assigned the same reference numerals and descriptions thereof will be omitted.

  The power conversion device 1 according to the present embodiment is mounted on, for example, an electric vehicle, and a secondary side provided with a primary side (an external resonant circuit provided on the main body side provided with the battery 2 or on the ground) and the electric motor 3 Wireless power transfer is performed between the side (wheel side), and the power obtained by the wireless power transfer is converted into three-phase AC power and supplied to the motor 3. Although non-patent document 1 describes wireless power transmission from an external resonance circuit provided on the ground to an electric vehicle, no specific circuit configuration or control method is described.

  The power conversion device 1 shown in FIG. 1 is different from the power conversion device 1A shown in FIG. 7 in the external power reception resonance circuit 31, single phase converter 34, step-up DC-DC converter 35, capacitor 37, current detector 38. And the addition of the voltage detector 39, and the primary side microcomputer 18A and the secondary side microcomputer 43A are respectively changed to the primary side microcomputer 18 (primary side control unit) and the secondary side microcomputer 43 (secondary side control unit) The point is different. The external power reception resonance circuit 31, the single phase converter 34, the step-up DC-DC converter 35, the capacitor 37, the current detector 38 and the voltage detector 39 are provided on the secondary side.

  A single phase converter 34 is connected between the external power reception resonant circuit 31 and the secondary side DC capacitor 25. The external power reception resonant circuit 31 is configured by connecting an inductor 32 and a capacitor 33 in series. The external power reception resonant circuit 31 performs wireless power transmission with an external resonant circuit (not shown) provided on the ground.

  Single-phase converter 34 is formed of switching elements Q9 to Q12 in which diodes are respectively connected in antiparallel. Switching element Q9 and switching element Q10 are connected in series, and switching element Q11 and switching element Q12 are connected in series. A series body composed of switching elements Q9 and Q10 and a series body composed of switching elements Q11 and Q12 are connected in parallel to secondary side DC capacitor 25. The connection point between switching element Q9 and switching element Q10 and the connection point between switching element Q11 and switching element Q12 are connected to resonance circuit 31 for external power reception.

  A step-up DC-DC converter 35 is connected between the capacitor 37 and the secondary side DC capacitor 25. The step-up DC-DC converter 35 includes switching elements Q13 and Q14 in which diodes are respectively connected in anti-parallel, and an inductor 36. Switching element Q13 and switching element Q14 are connected in series, and a series body of switching element Q13 and switching element Q14 is connected in parallel to secondary-side DC capacitor 25. Further, one end of the inductor 36 is connected to a connection point between the switching element Q13 and the switching element Q14. The capacitor 37 has one end connected to the other end of the inductor 36 and the other end connected to the other end different from one end connected to the switching element Q13 of the switching element Q14.

  The current detector 38 detects the current Ic flowing through the capacitor 37, and outputs the detection result to the secondary microcomputer 43. The voltage detector 39 detects the voltage E3 of the capacitor 37, and outputs the detection result to the secondary microcomputer 43.

The primary side microcomputer 18 outputs gate signals for controlling on / off of switching elements constituting the step-up / step-down DC-DC converter 11 and the primary side single-phase inverter 13. Further, the primary side microcomputer 18 calculates the state of charge (SOC) of the battery 2 and causes the primary side wireless device 17 to transmit the calculated state of charge SOC and the torque command T ^* to the secondary side wireless device 42.

The secondary side microcomputer 43 is detected by the voltage E2 detected by the voltage detector 28, the speed ω detected by the speed detector 29, the current Ic detected by the current detector 38, and the voltage detector 39. The voltage E3, the phase of the current I2 detected by the phase detector 41, and the torque command T ^* and the charging rate SOC received by the secondary radio 42 from the primary radio 17 are input. The secondary side microcomputer 43 controls on / off of switching elements constituting each of the secondary side single phase inverter 24, the three phase inverter 26, the single phase converter 34 and the step-up DC-DC converter 35 based on these inputs. Generate a signal. Further, the secondary microcomputer 43 calculates a voltage command V1 ^* that instructs the voltage V1 and a pulse width ratio α of the voltage V2. Then, the secondary side microcomputer 43 causes the secondary side wireless device 42 to transmit the calculated voltage command V1 ^* to the primary side wireless device 17. Further, the secondary side microcomputer 43 controls the secondary side single phase inverter 24 so that the voltage V2 corresponding to the calculated pulse width ratio α is output.

The primary side microcomputer 18 controls the primary side single-phase inverter 13 so that the voltage V1 corresponding to the voltage command V1 ^* received by the primary side wireless device 17 from the secondary side wireless device 42 is output.

  Next, the configuration and operation of the secondary microcomputer 43 will be described in more detail.

  FIG. 2 is a diagram showing a configuration example of a duty calculation block 50 that calculates the duty Dch of switching of the switching elements Q13 and Q14 configuring the step-up DC-DC converter 35. The duty calculation block 50 shown in FIG. 2 is included in the secondary microcomputer 43.

  The duty calculation block 50 shown in FIG. 2 includes subtractors 51 and 53 and PI control units 52 and 54.

The subtractor 51 receives the voltage E2 detected by the voltage detector 28 and the voltage command E2 ^* instructing the voltage E2, and outputs the deviation between the voltage command E2 ^* and the voltage E2 to the PI control unit 52.

The PI control unit 52 generates a current command Ic ^* that instructs the current Ic such that the deviation between the voltage command E2 ^* output from the subtractor 51 and the voltage E2 becomes zero by means of proportional integral (PI) control, It outputs to the subtracter 53.

The subtractor 53 receives the current command Ic ^* output from the PI control unit 52 and the current Ic detected by the current detector 38, and outputs the deviation between the current Ic and the current command Ic ^* to the PI control unit 54. Output.

The PI control unit 54 generates a duty Dch by which the deviation between the current Ic output from the subtractor 53 and the current command Ic ^* becomes zero by PI control.

The secondary microcomputer 43 generates a gate signal according to the duty Dch generated by the PI control unit 54 as the gate signal G13 of the switching element Q13, and outputs the gate signal to the switching element Q13. Further, the secondary side microcomputer 43 generates, as a gate signal of the switching element Q14, a signal obtained by inverting the gate signal G13, and outputs the signal to the switching element Q14. That is, the secondary side microcomputer 43 controls the step-up DC-DC converter 35 such that the current Ic that causes the voltage E2 to follow the voltage command E2 ^* flows in the capacitor 37. By this, the voltage E2 of the secondary side DC capacitor 25 can be made to follow the voltage command E2 ^* .

By controlling the step-up DC-DC converter 35 such that the current Ic that allows the voltage E2 to follow the voltage command E2 ^* flows to the capacitor 37, the power stored in the capacitor 37 during the powering of the motor 3 is three-phase AC It can be converted into electric power and supplied to the motor 3, and also, during regeneration of the motor 3, three-phase AC power output from the motor 3 can be converted into DC power and accumulated in the capacitor 37. Therefore, between the step-up / step-down DC-DC converter 11, the primary side single phase inverter 13, the primary resonance circuit 14, the secondary resonance circuit 21, the secondary side single phase inverter 24, the three phase inverter 26, etc. Compared to wireless power transmission, power transmission can be performed with low loss, and power transmission efficiency can be improved.

FIG. 3 is a diagram showing a configuration example of a power command calculation block 60 that calculates a power command P ^* that specifies the power P to be transmitted between the primary resonant circuit 14 and the secondary resonant circuit 21. The power command calculation block 60 shown in FIG. 3 is included in the secondary side microcomputer 43.

  The power command calculation block 60 shown in FIG. 3 includes a subtractor 61 and a PI control unit 62.

Subtractor 61 includes a voltage E3 which is detected by the voltage detector 39, and the voltage command E3 ^* instructing a voltage E3 and outputs a deviation between the voltage command E3 ^* and the voltage E3 in the PI control unit 62.

PI control unit 62 generates power command P ^* such that the deviation between voltage command E3 ^* output from subtractor 61 and voltage E3 becomes zero by PI control.

By generating power command P ^* such that the deviation between voltage command E3 ^* and voltage E3 is zero, when voltage E3 <voltage command E3 ^* , the difference between voltage E3 and voltage command E3 ^* is generated. Corresponding power is supplied from the primary resonant circuit 14 to the secondary resonant circuit 21. When voltage E3> voltage command E3 ^* , power corresponding to the deviation between voltage E3 and voltage command E3 ^* is supplied from secondary resonance circuit 21 to primary resonance circuit 14. Therefore, voltage E3 of capacitor 37 can be made to follow voltage command E3 ^* .

Next, a method of calculating voltage command E3 ^* will be described.

It is assumed that the electric vehicle on which the power conversion device 10 is mounted starts to accelerate from the state where the voltage E3 is the maximum value E3max, and the kinetic energy of the electric vehicle and the charge / discharge energy of the capacitor 37 are equal. In this case, the voltage E3 is expressed by the following equation (2) using the value m corresponding to the weight of the electric vehicle, the capacitance C of the capacitor 37, the speed ω of the motor 3 and the maximum value E3max of the voltage E3. .

Assuming that voltage E3 in equation (2) is voltage command E3 ^* , a power command P ^* corresponding to the loss of motor 3, three-phase inverter 26, step-up DC-DC converter 35, etc. is generated. However, equation (2) itself may change depending on various conditions such as whether the electric vehicle is traveling uphill or downhill, and it is difficult to grasp an accurate value. .

  Therefore, m / C is defined as K1, and K1 is calculated so that the speed ω of the motor 3 becomes the maximum speed ωmax when the voltage E3 is the minimum value E3 min. Assuming that m / C = K1, E3 = E3 min, and ω = ωmax in the equation (2), K1 is represented by the following equation (3).

The voltage command E3 ^* is expressed by the following equation (4) using the equations (2) and (3). FIG. 4 is a diagram showing a waveform example of the voltage command E3 ^* , which is calculated according to the equation (4).

FIG. 5 is a diagram showing a voltage command / pulse width ratio calculation block 70 that calculates the voltage command V1 ^* and the pulse width ratio α. The voltage command / pulse width ratio calculation block 70 shown in FIG. 5 is included in the secondary microcomputer 43.

The voltage command / pulse width ratio calculation block 70 receives the power command P ^* calculated by the power command calculation block 60, and calculates the voltage command V1 ^* and the pulse width ratio α based on the input power command P ^* . Hereinafter, a method of calculating voltage command V1 ^* and pulse width ratio α will be described.

First, a method of calculating voltage command V1 ^* will be described.

  In the case of the phase shift system, the power P transmitted between the primary resonant circuit 14 and the secondary resonant circuit 21 is expressed by the following equation (5).

Assuming that α = αr, P = | P ^* |, V1 = V1 ^* from the equation (5), the voltage command V1 ^* is expressed by the following equation (6). In addition, K2 in Formula (6) is represented by the following Formula (7). Here, αr is a basic pulse width ratio, which is a predetermined value determined in advance. The basic pulse width ratio αr is preferably closer to 1 to increase the transmission efficiency, but secures a control margin to compensate for the control delay of the voltage V1 caused by the communication delay between the primary side and the secondary side. In order to do so, it is appropriate to set it to about 0.8.

From the equation (6), when the voltage command V1 ^* is zero, the current I2 does not flow, so that the phase detection by the phase detector 41 becomes impossible. Therefore, voltage command / pulse width ratio calculation block 70 limits voltage command V1 ^* to a predetermined value (a voltage equal to or higher than the voltage through which current I2 can be detected by phase detector 41).

  Next, a method of calculating the pulse width ratio α will be described.

  The pulse width ratio α is expressed by the following equation (8) from the equations (5) and (7).

A voltage command V1 ^* passed through a first-order lag filter that gives a delay corresponding to the communication time between the primary side wireless device 17 and the secondary side wireless device 42 is a voltage command V1LPF ^* , where P = P ^* , V1 = V1 LPF ^If equation (8) is approximated as ^* , the following equation (9) is obtained.

  When the pulse width ratio α is positive, the secondary side microcomputer 43 assumes that the phase of the voltage V1 is the same phase as the phase of the current I2, and when the pulse width ratio α is negative, the phase of the voltage V1 is the current I2 The secondary side single-phase inverter 24 is controlled such that the voltage V2 corresponding to the pulse width ratio α is output, assuming that the phase is opposite to that of the phase. In other words, when the pulse width ratio α is positive, power is supplied from the primary resonant circuit 14 to the secondary resonant circuit 21. When the pulse width ratio α is negative, the secondary resonant circuit 21 to the primary resonant circuit 14 Power is supplied.

FIG. 6 is a diagram showing a waveform example of voltage command V1 ^* and pulse width ratio α. FIG. 6 shows a waveform example of the voltage command V1 ^* calculated according to the equation (6) and the pulse width ratio α calculated according to the equation (9).

When the voltage command V1 ^* is not limited to the minimum value, the pulse width ratio α becomes 0.8 or −0.8 when the basic pulse width ratio αr = 0.8. For example, assuming that the basic pulse width ratio αr = 1.0 and the pulse width ratio α is 1.0 or −1.0, the secondary side single-phase inverter 24 performs switching at the timing of I 2 00. The loss is minimized and the efficiency is high. However, when the pulse width ratio α is 1.0 or −1.0, the pulse width ratio α can not be manipulated, so the primary resonant circuit 14 and the secondary resonant circuit 21 can be operated only by operating the voltage command V1 ^*. And the power P transmitted between them. Since there is a communication delay in the wireless communication between the primary side wireless device 17 and the secondary side wireless device 42, the secondary side microcomputer 43 calculates the voltage command V1 ^*, and the primary side single phase inverter 13 actually A delay occurs until the voltage V1 following the voltage command V1 ^* is output. Therefore, in the transition state in which power command P ^* is changing, power P and power command P ^* do not match. By setting the basic pulse width ratio αr = 0.8, the pulse width ratio α can be manipulated even in the transition state in which the power command P ^* changes, and the power P and the power command P ^* are made to coincide with each other. be able to.

  Next, a control method of the single phase converter 34 will be described.

  The secondary side microcomputer 43 turns on the switching elements Q9 and Q11 or turns on the switching elements Q10 and Q12 if the charging rate SOC of the battery 2 transmitted from the primary side wireless device 17 is equal to or higher than a predetermined value. Thus, the power from the external power reception resonant circuit 31 is cut off. That is, the power supply from the external resonant circuit is not received. Further, when the state of charge SOC of battery 2 is less than the predetermined value, secondary side microcomputer 43 turns off switching elements Q9 to Q12, and receives power from the external resonance circuit via external power reception resonance circuit 31. Do. The power supplied from the external resonant circuit is transmitted from the secondary side to the primary side to charge the battery 2.

As described above, in the present embodiment, the power conversion device 1 controls the step-up DC-DC converter 35 so that the current Ic flows to the capacitor 37 such that the voltage E2 follows the voltage command E2 ^*. 43 is provided.

By controlling the step-up DC-DC converter 35 such that the current Ic that allows the voltage E2 to follow the voltage command E2 ^* flows to the capacitor 37, the electric power stored in the capacitor 37 can be three-phase AC It can be converted into electric power and supplied to the motor 3, and also, during regeneration of the motor 3, three-phase AC power output from the motor 3 can be converted into DC power and accumulated in the capacitor 37. Therefore, between the step-up / step-down DC-DC converter 11, the primary side single phase inverter 13, the primary resonance circuit 14, the secondary resonance circuit 21, the secondary side single phase inverter 24, the three phase inverter 26, etc. Compared to wireless power transmission, power transmission can be performed with low loss, and power transmission efficiency can be improved.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, functions included in each block can be rearranged so as not to be logically inconsistent, and a plurality of blocks can be combined into one or divided.

DESCRIPTION OF SYMBOLS 1 power converter 2 battery 3 motor 11 buck-boost DC-DC converter 12 primary side DC capacitor 13 primary side single phase inverter 14 primary resonance circuit 15,23,33 capacitor 16,22,32,36 inductor 17 primary side wireless device 18 Primary side microcomputer 21 Secondary resonant circuit 24 Secondary side single phase inverter 25 Secondary side DC capacitor 26 Three phase inverter 27, 38 Current detector 28, 39 Voltage detector 29 Speed detector 31 Resonant circuit for external power reception 34 Single Phase converter 35 Step-up DC-DC converter 37 Capacitor 41 Phase detector 42 Secondary side radio 43 Secondary side microcomputer 50 Duty operation block 51, 53, 61 Subtractor 52, 54, 62 PI control unit 60 Power command operation block 70 Voltage command / pulse width ratio calculation block

Claims (6)

A power conversion device that performs wireless power transfer between a primary side provided with a battery and a secondary side provided with a motor,
Primary side DC capacitor,
A primary resonant circuit having a resonant frequency f;
A step-up / step-down DC-DC converter connected between the battery and the primary DC capacitor;
A primary side single-phase inverter connected between the primary side DC capacitor and the primary resonant circuit and outputting a voltage V1 having the same frequency as the resonant frequency f to the primary resonant circuit;
A secondary resonant circuit having the same resonant frequency f as the primary resonant circuit and magnetically coupled to the primary resonant circuit;
Secondary side DC capacitor,
Capacitors,
A secondary side single phase inverter connected between the secondary resonant circuit and the secondary side DC capacitor and outputting a voltage V2 having the same frequency as the resonant frequency f to the secondary resonant circuit;
A three-phase inverter connected between the secondary side DC capacitor and the motor;
A step-up DC-DC converter connected between the secondary side DC capacitor and the capacitor;
A secondary side control unit for controlling the step-up DC-DC converter so that a current Ic such that the voltage E2 follows the voltage command E2 ^* instructing the voltage E2 of the secondary side DC capacitor flows to the capacitor And a power converter. In the power converter according to claim 1,
With primary side radio,
A secondary side wireless device performing wireless communication with the primary side wireless device;
And a primary side control unit for transmitting a torque command T ^* for instructing the torque of the motor to the primary side wireless device to the secondary side wireless device,
The secondary side control unit is configured to determine the phase of the current I2 flowing through the secondary side single phase inverter, the voltage E2, the voltage E3 of the capacitor, the current Ic, the speed ω of the motor, and the secondary Voltage command V1 for controlling the secondary side single-phase inverter, the three-phase inverter, and the step-up DC-DC converter based on the torque command T ^* received via the wireless device, and for instructing the voltage V1 A power conversion apparatus characterized by generating ^* and causing the secondary side wireless device to transmit to the primary side wireless device. In the power converter according to claim 2,
The secondary side control unit instructs the power P transmitted between the primary resonant circuit and the secondary resonant circuit based on the deviation between the voltage E3 and the voltage command E3 ^* instructing the voltage E3 ^. Power command P ^* is generated, and based on the maximum value ωmax of the speed ω, the maximum value E3max of the voltage E3, and the minimum value E3min of the voltage E3, the voltage command E3 ^* is expressed by the equations (1), (2) The power converter according to claim 1.

In the power converter according to claim 3,
The secondary side control unit is configured to calculate a mutual inductance M between the primary resonant circuit and the secondary resonant circuit, an absolute value | P ^* | of the power command P ^* , and a basic pulse width ratio αr which is a predetermined value. Based on the above, the voltage command V1 ^* is calculated according to the equations (3) and (4), and the calculated voltage command V1 ^* is limited to be a predetermined value or more.

In the power converter according to claim 4,
The secondary side control unit controls the pulse width ratio α of the voltage V2 based on the voltage command V1 LPF ^* obtained by delaying the voltage command V1 ^* by the communication time between the primary side wireless device and the secondary side wireless device. Calculated according to the following equation (5),
The secondary side single-phase inverter sets the phase of the voltage V1 to the same phase as the current I2 when the pulse width ratio α is positive, and the voltage V1 when the pulse width ratio α is negative. A voltage V2 having a magnitude corresponding to the pulse width ratio α, and the phase of the current I2 being reverse to the phase of the current I2.

The power converter according to any one of claims 1 to 5.
A resonant circuit for external power reception,
The single-phase converter further includes a single-phase converter connected between the resonance circuit for external power reception and the secondary-side DC capacitor,
The primary side radio transmits the charging rate of the battery to the secondary side radio;
The said secondary side control part is said single phase converter so that the electric power from the said resonance circuit for external power reception may be interrupted, when the charging rate received via the said secondary side radio | wireless machine is more than predetermined value And controlling the operation of the single-phase converter so as to receive power from the external power reception resonant circuit if the charging rate is less than a predetermined value.

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