JP2026010562A - Power System - Google Patents

Abstract

The present invention aims to suppress the increase in noise caused by ripple current and motor noise and vibration.
[Solution] The power system includes a power storage device, a motor, an inverter provided between the power storage device and the motor and having a plurality of switching elements, and a control device that controls the inverter. During ripple temperature rise control using a ripple current to raise the temperature of at least one of the motor, the inverter, and the power storage device, the control device controls the inverter by setting the frequency of the ripple current so that the frequency range of noise generated by the ripple current is outside the resonant frequency range of the motor, which is determined based on the motor temperature.
[Selected Figure] Figure 2

Description

This disclosure relates to power systems.

Conventionally, a power system has been proposed that includes a power storage device, a motor, and a boost converter and inverter that are provided between the power storage device and the motor and each have multiple switching elements (see, for example, Patent Document 1). In this power system, when the ripple temperature rise start condition is met, the boost converter's switching elements are switched to generate a ripple current in the power storage device, thereby raising the temperature of the power storage device.

Patent No. 5293820

In the power system described above, if the frequency range of noise generated by ripple current overlaps with the resonant frequency range of the motor, the peak value of the noise generated by the ripple current and the motor's noise and vibration tend to increase. The power system disclosed herein primarily aims to suppress increases in the noise generated by ripple current and the motor's noise and vibration.

The power system disclosed herein employs the following measures to achieve the above-mentioned primary objectives:

The power system of the present disclosure includes:
A power system including: a power storage device; a motor; an inverter provided between the power storage device and the motor and having a plurality of switching elements; and a control device that controls the inverter,
When performing ripple temperature rise control using a ripple current to raise the temperature of at least one of the motor, the inverter, and the power storage device, the control device controls the inverter by setting a frequency of the ripple current so that a frequency range of noise generated by the ripple current is outside a resonance frequency range of the motor based on a temperature of the motor.
The gist of this is as follows.

In the power system disclosed herein, during ripple heating control using a ripple current to heat at least one of the motor, inverter, and power storage device, the inverter is controlled by setting the frequency of the ripple current so that the frequency range of noise generated by the ripple current is outside the motor's resonant frequency range, which is based on the motor's temperature. Through experiments, analysis, machine learning, and other methods, the inventors have discovered that the higher the motor's temperature, the lower the motor's resonant frequency range. Therefore, by performing the above-described control, it is possible to prevent the frequency range of noise generated by the ripple current from overlapping with the motor's resonant frequency range, thereby preventing the noise generated by the ripple current and the motor's noise and vibration from increasing.

1 is a schematic configuration diagram of a power system 20 and a charging stand 80 according to an embodiment. 4 is a flowchart showing an example of a ripple temperature increase control routine. FIG. 10 is an explanatory diagram showing an example of a state during ripple temperature increase control.

A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a power system 20 and a charging stand 80 according to an embodiment of the present disclosure. The power system 20 according to the embodiment is mounted on an electric vehicle or a hybrid vehicle, and includes a motor 22, an inverter 24, a battery 26 as a power storage device, a charging connector 40, a relay 46, and a system electronic control unit (hereinafter referred to as "system ECU") 50 as a control device. The power system 20 is capable of charging the battery 26 using power from a charging stand 80 installed at a home, a charging station, or the like.

The motor 22 is configured as a three-phase AC motor and includes a rotor with a permanent magnet embedded in the rotor core and a stator with three-phase (U-, V-, and W-phase) coils wound around the stator core. The inverter 24 is connected to the positive line 28p and negative line 28n, which are connected to the battery 26. The inverter 24 includes six switching elements, transistors T11-T16, and six diodes D11-D16 connected in parallel to the six transistors T11-T16. The transistors T11-T16 are arranged in pairs, two on the source side and two on the sink side of the positive line 28p and the negative line 28n. The connection points of the two transistors in each pair are connected to the three-phase (U-, V-, and W-phase) coils of the motor 22. A smoothing capacitor 30 is connected to the positive line 28p and the negative line 28n. Battery 26 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The positive and negative terminals of battery 26 are connected to positive and negative lines 28p and 28n.

The charging connector 40 is configured to be connectable to the stand connector 82 of the charging stand 80. The charging connector 40 is connected to the neutral point of the motor 22 via the positive line 42p and a relay 46, and is connected to the negative line 28n via the negative line 42n. A smoothing capacitor 44 is connected to the positive line 42p and the negative line 42n.

Relay 46 connects and disconnects the neutral point of motor 22 from positive line 42p by turning it on and off. When relay 46 is on, a three-phase (U-phase, V-phase, W-phase) boost converter is formed by motor 22 and inverter 24 between positive line 42p and negative line 42n and positive line 28p and negative line 28n. Specifically, the U-phase boost converter is formed by the U-phase coil of motor 22 and transistors T11 and T14, the V-phase boost converter is formed by the V-phase coil of motor 22 and transistors T12 and T15, and the W-phase boost converter is formed by the W-phase coil of motor 22 and transistors T13 and T16.

The system ECU 50 includes a microcomputer with a CPU, ROM, RAM, flash memory, input/output ports, and communication ports, as well as various drive circuits and logic ICs. The system ECU 50 receives signals from various sensors. These sensors include a rotational position sensor 22a that detects the rotational position θm of the rotor of the motor 22, current sensors 22u, 22v, and 22w that detect the phase currents Iu, Iv, and Iw of each phase of the motor 22, and a temperature sensor 22t that detects the temperature Tm of the motor 22. Other sensors include a voltage sensor 26v that detects the voltage Vb of the battery 26, a current sensor 26i that detects the current Ib of the battery 26, and a temperature sensor 26t that detects the temperature Tb of the battery 26. Other sensors include a voltage sensor 30v that detects the voltage VH of the capacitor 30 and a voltage sensor 44v that detects the voltage VL of the capacitor 44. The system ECU 50 outputs switching control signals to transistors T11 to T16 of the inverter 24 and a control signal to the relay 46. The system ECU 50 calculates the battery 26's power storage percentage SOC based on the integrated value of the battery 26's current Ib. The system ECU 50 is capable of communicating with a station electronic control unit (hereinafter referred to as "station ECU") 86 of the charging station 80.

The charging stand 80 includes a stand connector 82, a power supply device 84, and a stand ECU 86. The stand connector 82 is configured to be connectable to the charging connector 40 of the power system 20. The power supply device 84 is connected to an AC power source, such as a household power source or a commercial power source, and is configured to convert AC power from the AC power source to DC power, adjust the output power (output voltage and output current), and output the DC power to the stand connector 82. The stand ECU 86 is configured similarly to the system ECU 50. Signals from various sensors are input to the stand ECU 86. Examples of the various sensors include a voltage sensor (not shown) that detects the output voltage Vs of the power supply device 84 and a current sensor (not shown) that detects the output current Is of the power supply device 84. The stand ECU 86 outputs a control signal to the power supply device 84. As described above, the stand ECU 86 is capable of communicating with the system ECU 50 of the power system 20.

In the power system 20 of this embodiment, when external charging is performed to charge the battery 26 using power from the charging stand 80, switching control is performed on transistors T11 to T16 of the inverter 24 so that the power supplied from the power supply device 84 of the charging stand 80 to the neutral point of the motor 22 is boosted by the three-phase boost converter (motor 22 and inverter 24) and then supplied to the battery 26.

Next, we will explain the operation of the power system 20 of this embodiment, particularly the operation when external charging is performed and ripple temperature rise control is executed, which uses ripple current to raise the temperature of at least one of the motor 22, inverter 24, and battery 26. Ripple temperature rise control, for example, involves superimposing ripple current on the input/output current of the battery 26 to raise the temperature of the battery 26. A temperature rise request for the battery 26 is issued, for example, when the temperature Tb of the battery 26 is equal to or lower than the threshold value Tblo. Figure 2 is a flowchart showing an example of a ripple temperature rise control routine repeatedly executed by the system ECU 50 when external charging is performed and ripple temperature rise control is executed.

When this routine is executed, the system ECU 50 first sets the resonant frequency range Rmr of the motor 22 based on the temperature Tm of the motor 22 (step S100). Here, the resonant frequency range Rmr of the motor 22 is set by, for example, applying the temperature Tm of the motor 22 to a map that has been determined in advance through experiments, analysis, machine learning, etc. as the relationship between the temperature Tm of the motor 22 and the resonant frequency range Rmr of the motor 22, and deriving the corresponding resonant frequency range Rmr of the motor 22. Based on the results of experiments, analysis, machine learning, etc. conducted by the inventors, the resonant frequency range Rmr of the motor 22 is set to be lower as the temperature Tm of the motor 22 is higher.

Once the resonant frequency range Rmr of the motor 22 is set in this manner, the ripple center frequency Fc and ripple dispersion width Fd are set (step S110). Here, the ripple center frequency Fc is the center frequency of the ripple current in the ripple temperature rise control (the frequency at which ripple noise, which is noise generated by the ripple current, peaks). The ripple noise frequency ranges (Fc±Fd), (2Fc±2Fd), ... defined by the ripple center frequency Fc and the ripple dispersion width Fd are each a relatively large range of ripple noise (greater than or equal to a predetermined value) centered on a natural number multiple of the ripple center frequency Fc. In this embodiment, the ripple center frequency Fc and the ripple dispersion width Fd are set so that the ripple noise frequency ranges (Fc±Fd), (2Fc±2Fd), ... do not overlap with the resonant frequency range Rmr of the motor 22. In this case, for example, the ripple center frequency Fc may be lowered and the ripple dispersion width Fd may be narrowed as the temperature Tm of the motor 22 increases, or the ripple dispersion width Fd may be constant regardless of the temperature Tm of the motor 22 and the ripple center frequency Fc may be lowered as the temperature Tm of the motor 22 increases. Note that the ripple center frequency Fc depends on the switching frequency and the phase shift amount of the phase currents Iu, Iv, and Iw of the U-phase, V-phase, and W-phase boost converters when controlling the switching of the transistors T11 to T16 of the inverter 24, and the ripple dispersion width Fd depends on the random dispersion width of the switching frequency and the random dispersion width of the phase shift amount of the phase currents Iu, Iv, and Iw of the U-phase, V-phase, and W-phase boost converters when controlling the switching of the transistors T11 to T16.

Then, the inverter 24 is controlled using the set ripple center frequency Fc and ripple dispersion width Fd (step S120), and this routine ends. In controlling the inverter 24, power from the charging station 80 is boosted by the motor 22 and inverter 24 and supplied to the battery 26, and the switching of the inverter 24's transistors T11-T16 is controlled so that the ripple noise falls within the frequency range (Fc±Fd), (2Fc±2Fd), etc. Because the resonant frequency range Rmr of the motor 22 changes based on the temperature Tm of the motor 22, controlling the switching of the inverter 24's transistors T11-T16 in this manner can suppress increases in ripple noise and motor 22 noise and vibration, even if the temperature Tm of the motor 22 changes due to ripple temperature increase control.

Figure 3 is an explanatory diagram showing an example of ripple temperature rise control. Figure 3(A) shows the state when the temperature Tm of the motor 22 is temperature Tm1 in the embodiment and the comparative embodiment. Figure 3(B) shows the state when the temperature Tm of the motor 22 is temperature Tm2, which is higher than temperature Tm1, in the comparative embodiment. Figure 3(C) shows the state when the temperature Tm of the motor 22 is temperature Tm2 in the embodiment. In the comparative embodiment, the ripple center frequency Fc and the ripple dispersion width Fd are constant regardless of the temperature Tm of the motor 22. When the temperature Tm of the motor 22 is temperature Tm1 in the embodiment and the comparative embodiment, as shown in Figure 3(A), the frequency range of the ripple noise (Fc±Fd), (2Fc±2Fd), etc. does not overlap with the resonant frequency range Rmr of the motor 22, thereby suppressing the peak value (maximum value) of the ripple noise. In the comparative example, when the temperature Tm of the motor 22 is Tm2, as shown in FIG. 3(B), the resonant frequency range Rmr decreases as the temperature Tm of the motor 22 increases, causing the ripple noise frequency range (Fc±Fd), (2Fc±2Fd), ... to overlap with the resonant frequency range Rmr of the motor 22, resulting in a larger peak value of the ripple noise. In the embodiment, when the temperature Tm of the motor 22 is Tm2, as shown in FIG. 3(C), the resonant frequency range Rmr of the motor 22 decreases as the temperature Tm of the motor 22 increases, thereby lowering the ripple center frequency Fc and narrowing the ripple dispersion width Fd, preventing the ripple noise frequency range (Fc±Fd), (2Fc±2Fd), ... from overlapping with the resonant frequency range Rmr of the motor 22. As a result, the peak value of the ripple noise is suppressed compared to FIG. 3(B).

In the power system 20 of the embodiment described above, during ripple temperature rise control, the resonant frequency range Rmr of the motor 22 is set based on the temperature Tm of the motor 22, and the ripple center frequency Fc and ripple dispersion width Fd are set so that the ripple noise frequency range (Fc±Fd), (2Fc±2Fd), etc. does not overlap with the resonant frequency range Rmr of the motor 22. The set ripple center frequency Fc and ripple dispersion width Fd are used to control the switching of the transistors T11 to T16 of the inverter 24. By controlling the switching of the transistors T11 to T16 of the inverter 24 in this manner, it is possible to suppress increases in ripple noise and noise/vibration of the motor 22, even if the temperature Tm of the motor 22 changes due to ripple temperature rise control.

In the above-described embodiment, processing when external charging is being performed and ripple temperature increase control is being executed has been described. However, similarly, when external charging is being performed and ripple temperature increase control is not being executed, or when external charging is not being performed, the ripple center frequency Fc and ripple distribution width Fd may be set so that the ripple noise frequency range (Fc±Fd), (2Fc±2Fd), ... does not overlap with the resonant frequency range Rmr of the motor 22, and switching control of transistors T11 to T16 of the inverter 24 may be performed.

Although not described in the above embodiment, the power system 20 may further include a heat transfer device that transfers heat from the motor 22 and the inverter 24 to the battery 26.

In the above-described embodiment, the power system 20 uses a battery 26 as the power storage device, but this is not limited to this. For example, a capacitor or the like may also be used as the power storage device.

The following explains the correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section. In the embodiment, the battery 26 corresponds to the "power storage device," the motor 22 corresponds to the "motor," the inverter 24 corresponds to the "inverter," and the system ECU 50 corresponds to the "control device."

The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, as the embodiments are examples used to specifically explain the form for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

The above describes the forms for implementing this disclosure using embodiments, but the disclosure is not limited to these embodiments in any way, and it goes without saying that the disclosure can be implemented in various forms without departing from the spirit of the disclosure.

This disclosure can be used in the power system manufacturing industry, etc.

20 Power system, 22 Motor, 22a Rotational position sensor, 22t, 26t Temperature sensors, 22u, 22v, 22w, 26i Current sensors, 24 Inverter, 26 Battery (energy storage device), 26v, 30v, 44v Voltage sensors, 28n, 42n Negative line, 28p, 42p Positive line, 30, 44 Capacitor, 40 Charging connector, 46 Relay, 50 System ECU (control device), 80 Charging stand, 82 Stand connector, 84 Power supply device, 86 Stand ECU, D11 to D16 Diodes, T11 to T16 Transistors.

Claims (1)

A power system including: a power storage device; a motor; an inverter provided between the power storage device and the motor and having a plurality of switching elements; and a control device that controls the inverter,
When performing ripple temperature rise control using a ripple current to raise the temperature of at least one of the motor, the inverter, and the power storage device, the control device controls the inverter by setting a frequency of the ripple current so that a frequency range of noise generated by the ripple current is outside a resonance frequency range of the motor based on a temperature of the motor.
Power system.