JP7848738B2 - Isolated power supply unit, power supply system, and power control program - Google Patents

Description

This disclosure relates to an isolated power supply, a power supply system, and a power control program.

When external charging is performed, where the energy storage device is charged by an external power source located outside the power supply system, the voltage of the external power source may also be applied to the load drive device along with the energy storage device. In this case, parasitic capacitance may develop in the load drive device, potentially causing it to operate unintentionally. To avoid such a situation, a switching element that cuts off power to the load drive device during external charging may be controlled to the off state.

In this case, a power supply is required to provide the driving power necessary to operate the switching element during external charging. If this power supply is a switching power supply, noise will be generated from it during external charging. It is preferable to reduce such noise during external charging.

Therefore, a power supply system has been devised that reduces noise by intermittently operating a switching power supply during external charging. Such a power supply system is described, for example, in Patent Document 1.

Japanese Patent Publication No. 2022-118417

Incidentally, when switching power supplies are operated intermittently to reduce noise, it is possible to reduce noise in a specific frequency band, but not in other frequency bands. Therefore, there were cases where the predetermined noise standards could not be met in frequency bands other than the specific one.

This invention was made to solve the above problems, and its primary objective is to provide an isolated power supply, power supply system, and power control program that can suppress noise to meet the standards.

The first means for solving the above problem is an isolated power supply device for supplying power to a semiconductor device drive circuit, comprising: a primary winding connected to a DC power supply; a secondary winding magnetically coupled to the primary winding via a core; a control switch circuit that, when turned on, supplies power from the DC power supply to the primary winding and, when turned off, stops the power supply from the DC power supply to the primary winding; and a switch control unit that controls the on/off state of the control switch circuit. The switch control unit, upon receiving an operating state switching signal, controls the on/off state by changing the switching frequency to one that differs from the normal state and slowing the switching speed to one that is slower than the normal state, or by performing either one of these actions.

This allows for noise suppression during external charging by inputting an operating state switching signal. Alternatively, the noise frequency can be shifted to meet the required standards.

The second means is a power supply system capable of external charging, which charges a power storage device using an external power source, comprising: an inverter provided in the power path between the motor and the power storage device; a drive circuit for semiconductor switching elements constituting the inverter; an isolated power supply device that supplies power to the drive circuit; and a power control device that controls the isolated power supply device, wherein the isolated power supply device comprises: a primary winding connected to a DC power source; a secondary winding magnetically coupled to the primary winding via a core; and a control that, when turned on, supplies power from the DC power source to the primary winding, and when turned off, stops the power supply from the DC power source to the primary winding. The system comprises a power switch circuit and a switch control unit that controls the on/off state of the control switch circuit. During external charging, the semiconductor switching element of the inverter is switched on and off, thereby converting the power from the external power supply by the motor and the inverter and supplying it to the energy storage device. During external charging, the power control device inputs an operating state switching signal to the switch control unit. When the operating state switching signal is input, the switch control unit controls the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions.

This allows for noise suppression during external charging by inputting an operating state switching signal. Alternatively, the noise frequency can be shifted to meet the required standards.

The third means is a power control program implemented by an isolated power supply unit that supplies power to a semiconductor device's drive circuit, wherein the isolated power supply unit comprises a primary winding connected to a DC power supply, a secondary winding magnetically coupled to the primary winding via a core, a control switch circuit that, when turned on, supplies power from the DC power supply to the primary winding and, when turned off, stops the power supply from the DC power supply to the primary winding, and a switch control unit that controls the on/off state of the control switch circuit, and when an operating state switching signal is input to the isolated power supply unit, the switch control unit is instructed to control the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions.

This allows for noise suppression during external charging by inputting an operating state switching signal. Alternatively, the noise frequency can be shifted to meet the required standards.

Power supply system configuration diagram. Configuration diagram of the control device. Configuration diagram of a switching power supply. Flowchart of the power supply process. A diagram showing the relationship between noise level and frequency. Configuration diagram of the switching power supply according to the second embodiment. A flowchart of the power supply process in the second embodiment. A diagram showing the relationship between noise magnitude and frequency in the second embodiment. A flowchart of the power supply process in the third embodiment. A diagram showing the relationship between noise magnitude and frequency in the third embodiment.

The following describes embodiments of the isolated power supply device, power supply system, and power control program according to this disclosure, based on the drawings. In the following embodiments and modifications, parts that are identical or equivalent to each other are denoted by the same reference numerals in the drawings, and their descriptions are based on those same reference numerals. The isolated power supply device of this embodiment is installed in a power supply system for a mobile vehicle, such as an electric vehicle or a hybrid vehicle.

<First Embodiment>
As shown in Figure 1, the power supply system 10 includes a motor 11 as a rotating electric machine, an inverter 12 as a power converter, a high-voltage battery 20 as an energy storage device, and a control device 30. The motor 11 is connected to the inverter 12 and plays a role as the main engine of the mobile unit. The inverter 12 is a three-phase inverter and is connected to the high-voltage battery 20. The control device 30 controls the motor 11 by controlling the inverter 12. A detailed explanation follows below.

The motor 11 is a three-phase synchronous machine, comprising star-connected U, V, and W phase armature windings 11a to 11c and a rotor (not shown). The armature windings 11a to 11c of each phase are arranged with a 120° electrical angle offset from each other. The motor 11 is, for example, a permanent magnet synchronous machine. The rotor is capable of transmitting power to, for example, the drive wheels of a moving body. Therefore, the motor 11 serves as the source of torque that propels the moving body.

The inverter 12 is a three-phase full-bridge inverter equipped with three series connections (legs) of upper arm switches Sp and lower arm switches Sn, which are connected in parallel. An upper arm diode Dp, which is a freewheeling diode, is connected in antiparallel (reverse polarity) to the upper arm switch Sp, and a lower arm diode Dn, which is a freewheeling diode, is connected in antiparallel to the lower arm switch Sn. In this embodiment, each switch Sp and Sn is a semiconductor switch element (semiconductor device), for example, an IGBT, but it may also be a MOSFET. Note that the upper arm switch Sp and lower arm switch Sn may be collectively referred to as upper and lower arm switches Sp and Sn below.

The inverter 12 includes a smoothing capacitor 13. The high-potential terminal of the smoothing capacitor 13 is connected to the positive-side power supply path H1. The low-potential terminal of the smoothing capacitor 13 is connected to the negative-side power supply path L1. The smoothing capacitor 13 may also be located outside the inverter 12.

In each phase, the first ends of the armature windings 11a to 11c are connected to the connection point between the emitter, which is the low-potential terminal of the upper arm switch Sp, and the collector, which is the high-potential terminal of the lower arm switch Sn, via a conductive member 14 such as a busbar. The second ends of the armature windings 11a to 11c of each phase are connected to each other at the neutral point.

The collectors of the upper arm switches Sp of each phase are connected to the positive power supply path H1. The emitters of the lower arm switches Sn of each phase are connected to the negative power supply path L1. As a result, the inverter 12 is connected to the high-voltage battery 20 via the positive power supply path H1 and the negative power supply path L1.

The positive-side power supply path H1 and the negative-side power supply path L1 are equipped with a main switch SMR that switches between energizing and disconnecting the power supply in power supply paths H1 and L1. The main switch SMR is a mechanical relay switch, but a semiconductor switch may also be used.

The high-voltage battery 20 serves as a power source for rotating the rotor of the motor 11. The high-voltage battery 20 is a battery pack configured as a series connection of individual battery cells. The positive terminal of the high-voltage battery 20 is connected to the positive-side power supply path H1, and the negative terminal is connected to the negative-side power supply path L1. The terminal voltages (e.g., rated voltages) of each battery cell constituting the battery pack are set to be the same, for example. The battery cells are, for example, secondary batteries such as lithium-ion batteries.

Furthermore, the power supply system 10 includes an external charging mechanism 80 for connection to an external charger 100, which serves as an external power source. The external charging mechanism 80 includes an intret 82 and a relay 81. The intret 82 is connected via the relay 81 to power paths H1 and L1 between the high-voltage battery 20 and the inverter 12. The intret 82 is configured to supply power from the external charger 100 to the high-voltage battery 20 during external charging, when the main switch SMR and relay 81 are in the ON state (closed state, energized state). As shown in Figure 1, it may also be connected to the neutral point of the motor 11 to enable neutral point charging.

External charging is performed when the vehicle is connected to the external charger 100. The external charger 100 includes a connector 110, which is configured to connect to the vehicle's inlet 82. The external charger 100 is, for example, a DC power source, but may also be an AC power source. In this case, an AC/DC converter or the like is required in the external charger 100 or the power supply system 10. If an AC/DC converter is provided in the power supply system 10, some of the circuit elements constituting the motor 11 and inverter 12 may be reused. That is, the system may be configured to supply charging power to the inverter 12 via the motor 11, operate the inverter 12, convert the power using the motor 11 and inverter 12, and charge the high-voltage battery 20.

As shown in Figure 2, the control device 30 is mainly composed of a microcontroller unit (microcomputer) 31 and is powered by a low-voltage battery 21, which serves as a DC power source. The microcontroller unit 31 includes a CPU. The functions provided by the microcontroller unit 31 can be provided by software stored in a physical memory device and the computer that executes it, by software only, by hardware only, or a combination of both.

For example, when a microcontroller is provided by hardware electronic circuits, it can be provided by digital circuits containing numerous logic circuits, or by analog circuits. For instance, a microcontroller executes a program stored in a non-transitory tangible storage medium (NMT) that serves as its memory. The execution of the program then executes the method corresponding to the program. The memory is, for example, non-volatile memory. Furthermore, the program stored in the memory can be updated via communication networks such as the Internet, for example, through OTA (Over The Air).

The microcontroller 31 operates the inverter 12 to control the torque of the motor 11 to the command torque Trq* based on the detection values of various sensors (voltage sensor, current sensor, rotation angle sensor, etc.) not shown. Specifically, the control device 30 generates operation signals to turn each switch Sp and Sn constituting the inverter 12 on and off, and outputs these signals to the gate drive circuits DR (drive circuits) of each switch Sp and Sn via the interface unit 32.

The low-voltage battery 21 is a storage battery whose output voltage is lower than that of the high-voltage battery 20, and is, for example, a lead-acid battery. In this embodiment, the low-voltage battery 21 corresponds to a "DC power source".

The interface unit 32 has the function of transmitting signals between the high-voltage region, which comprises the motor 11, inverter 12, and high-voltage battery 20, and the low-voltage region, which comprises the control device 30 and low-voltage battery 21, while electrically isolating these two regions. The interface unit 32 is, for example, a photocoupler.

Next, the switching power supply 40 as an isolated power supply device will be described using Figures 2 and 3. The switching power supply 40 has the function of supplying drive power to the gate drive circuit DR that drives each switch Sp and Sn while isolating the high-voltage region from the low-voltage region. In this embodiment, the switching power supply 40 is a flyback type switching power supply.

As shown in Figure 3, the switching power supply 40 includes a power supply IC 41 and a control switch circuit 50. The power supply IC 41 and the control switch circuit 50 are located in the low-voltage region. The power supply IC 41 controls the control switch circuit 50 by switching signals. Therefore, the power supply IC 41 is the switch control unit. When the control switch circuit 50 is turned on, it supplies power from the low-voltage battery 21 to each transformer 60; when it is turned off, it stops the power supply from the low-voltage battery 21 to each transformer 60. The configuration of the control switch circuit 50 will be described later.

Next, the configuration of the transformer 60 will be described. The switching power supply 40 includes a transformer 60 that supplies power to the gate drive circuits DR of each switch Sp and Sn. The transformer 60 may be provided for each gate drive circuit DR, or some or all of them may be shared.

The transformer 60 comprises a primary winding (input winding 61), a secondary winding (output winding 62), and a feedback winding 63. The transformer 60 has a common core around which each winding 61, 62, and 63 are wound, and these windings are magnetically coupled by the common core. The input winding 61 and feedback winding 63 are located in the low-voltage region, while the output winding 62 is located in the high-voltage region.

The transformer 60 is provided with multiple terminals. The output terminals of the transformer 60 are connected to corresponding output windings 62. The first terminal T1 of the transformer 60 is connected to the second terminal T2 via the input winding 61. The third terminal T3 of the transformer 60 is connected to the fourth terminal T4 via the feedback winding 63. When the potential of the first terminal T1 relative to the second terminal T2 of the transformer 60 becomes high, an induced voltage is generated in the feedback winding 63 such that the potential of the fourth terminal T4 becomes higher than that of the third terminal T3 of the transformer 60.

The output terminal of transformer 60 is connected to the gate drive circuit DR via output diode 64 and output capacitor 65. The first terminal T1 of transformer 60 is connected to the positive terminal of the low-voltage battery 21 via wiring. The negative terminal of the low-voltage battery 21 is connected to ground. The second terminal T2 of transformer 60 is connected to the control switch circuit 50 via wiring.

The third terminal T3 of transformer 60 is connected to the anode of the feedback diode 71. The cathode of the feedback diode 71 is connected to ground via the feedback capacitor 72. The fourth terminal T4 of transformer 60 is also connected to ground via wiring.

Next, the control switch circuit 50 will be described with reference to Figure 3. The control switch circuit 50 includes a control switch 51. The control switch 51 is a voltage-controlled semiconductor switch, specifically an N-channel MOSFET. The drain of this control switch 51 is connected to the second terminal T2 of the transformer 60. The source of the control switch 51 is connected to ground.

The gate of this control switch 51 is connected to the power supply IC 41 via an electrical path L10, and a switching signal for controlling the on/off switching is input from the power supply IC 41 to the gate via the electrical path L10. Furthermore, the electrical path L10 is provided with a resistor circuit 52 for changing the switching speed when the switching signal switches from a high-level state to a low-level state or from a low-level state to a high-level state.

This resistor circuit 52 is configured to allow its resistance value to be changed. More specifically, the resistor circuit 52 comprises a first resistor R11 as a first resistive element, a first switch SW11 connected in series with the first resistor R11, a second resistor R12 as a second resistive element, and a second switch SW12 connected in series with the first resistor R11. The series connection of the first resistor R11 and the first switch SW11 is provided in the electrical path L10, and the series connection of the second resistor R12 and the second switch SW12 is connected in parallel to the series connection of the first resistor R11 and the first switch SW11. The resistance values of the first resistor R11 and the second resistor R12 are different; specifically, the resistance value of the second resistor R12 is greater than the resistance value of the first resistor R11.

The power supply IC 41 is configured to output a switching signal by turning on either the first switch SW11 or the second switch SW12. Therefore, when the second switch SW12 is turned on, the switching speed of the switching signal input to the control switch 51 can be slowed down compared to when the first switch SW11 is turned on.

Furthermore, in the control switch circuit 50, a snubber circuit 55 is connected in parallel to the control switch 51. The snubber circuit 55 is configured to allow for changeable time constants. More specifically, the snubber circuit 55 is composed of a first snubber circuit 53 and a second snubber circuit 54 connected in parallel. The first snubber circuit 53 and the second snubber circuit 54 are RC snubber circuits designed to absorb transient high voltages generated when the switch is interrupted.

To explain in more detail, the first snubber circuit 53 is composed of a series connection of a first snubber resistor R21 and a first snubber capacitor C21. The high-potential terminal of this first snubber circuit 53 (the terminal on the first snubber resistor R21 side) is connected to the high-potential terminal side (drain side) of the control switch 51. Conversely, the low-potential terminal of this first snubber circuit 53 (the terminal on the first snubber capacitor C21 side) is connected to the low-potential terminal side (source side, i.e., ground) of the control switch 51.

The second snubber circuit 54 is composed of a series connection of a second snubber resistor R22 and a second snubber capacitor C22. The high-potential terminal of this second snubber circuit 54 (the terminal on the second snubber resistor R22 side) is connected to the high-potential terminal side (drain side) of the control switch 51. On the other hand, the low-potential terminal of this second snubber circuit 54 (the terminal on the second snubber capacitor C22 side) is connected to the low-potential terminal side (source side, i.e., ground) of the control switch 51 via the third switch SW13, which acts as a snubber selector switch.

In other words, the third switch SW13 is connected in series with the second snubber circuit 54. When the third switch SW13 is turned on, it is electrically connected to the control switch 51, and when it is turned off, it is disconnected. The power supply IC 41 can control the on/off state of this third switch SW13. When the third switch SW13 is turned on, the time constant of the snubber circuit 55 can be increased compared to when it is off, making it possible to slow down the switching speed.

Furthermore, if the time constant of the snubber circuit 55 increases when the third switch SW13 is turned ON, the resistance values of the first snubber resistor R21, the second snubber resistor R22, the capacitance of the first snubber capacitor C21, and the capacitance of the second snubber capacitor C22 may be set arbitrarily. For example, the resistance value of the second snubber resistor R22 may be made greater than the resistance value of the first snubber resistor R21, and the capacitance of the second snubber capacitor C22 may be made greater than the capacitance of the first snubber capacitor C21.

The power supply IC 41 is an integrated circuit, and the functions it provides, like those of the microcontroller 31, can be provided by software stored in a physical memory device and the computer that executes it, by software alone, by hardware alone, or by a combination of both.

For example, the power supply IC 41 controls the control switch circuit 50 on and off according to a predetermined power supply control program. Specifically, the power supply IC 41 controls the control switch circuit 50 on and off to supply power from the low-voltage battery 21 to the gate drive circuit DR while electrically isolating the low-voltage battery 21 from the gate drive circuit DR.

In this embodiment, the power supply IC 41 sets the time ratio Ton/Tsw in the control switch circuit 50, where Tsw represents one switching period and Ton represents the on-time. It then outputs a switching signal corresponding to the set time ratio to the control switch circuit 50. In this embodiment, the power supply IC 41 corresponds to the "switch control unit." When a switching signal is input to the control switch circuit 50, the control switch 51 is controlled to turn on and off according to the switching signal input to its gate.

When the control switch 51 is turned on, power is supplied to the input winding 61 from the low-voltage battery 21. During this time, an induced voltage is generated in the feedback winding 63 such that the potential at the fourth terminal T4 of the transformer 60 is higher than that at the third terminal T3. In this case, the flow of current through the feedback winding 63 is restricted by the feedback diode 71, and magnetic energy is stored in the transformer 60. Similarly, the flow of current through the output winding 62 is restricted by the output diode 64.

On the other hand, when the control switch 51 is turned off, power supply from the low-voltage battery 21 to the input winding 61 is stopped. During this time, an induced voltage is generated in the feedback winding 63 such that the potential at the third terminal T3 of the transformer 60 is higher than that at the fourth terminal T4. This causes current to flow through the feedback winding 63. Similarly, current flows through the output winding 62, supplying drive power to the gate drive circuit DR.

Incidentally, the power supply system 10 is configured to be externally charged by connecting an external charger 100. When external charging is performed, if the charging voltage from the external charger 100 is applied to both the high-voltage battery 20 and the motor 11, parasitic capacitance may develop in the motor 11, potentially causing it to operate unintentionally. To avoid this situation, it is necessary to control the upper and lower arm switches Sp and Sn, which constitute the inverter 12, to the OFF state so that power to the motor 11 is cut off during external charging. Furthermore, during external charging, it may be possible to complementaryly control the on/off states of the upper and lower arm switches Sp and Sn, which constitute the inverter 12, by converting the AC current supplied from the external charger 100 to DC current using the inverter 12, etc.

In these cases, the switching power supply 40 needs to supply drive power to the gate drive circuit DR to operate the upper and lower arm switches Sp and Sn during external charging. However, the switching power supply 40 generates noise during operation due to the switching of the switches. It is preferable to reduce such noise during external charging. Specifically, a noise threshold Th is defined for each frequency band, and laws and regulations require that the noise not exceed the noise threshold Th. In particular, the requirements become stricter when the mobile body is stopped, i.e., during external charging, and it is generally necessary to suppress noise more than when the mobile body is moving. Therefore, the switching power supply 40 of this embodiment performs the following processing during external charging. This will be explained in detail below.

As shown in Figures 1 and 2, the higher-level control unit 200, such as the higher-level ECU or battery control ECU, notifies the control unit 30 when the start switch (ignition switch, power switch, etc.) is turned on. The microcontroller 31 of the control unit 30 outputs a drive command signal to the power supply IC 41 of the switching power supply 40 when the start switch is turned on. Furthermore, when the external charger 100 is connected and external charging is in progress (or is in a state where external charging is possible), the higher-level control unit 200 notifies the control unit 30 that external charging is in progress. Then, the microcontroller 31 of the control unit 30 outputs an operating state switching signal to the power supply IC 41 while external charging is in progress. Therefore, the microcontroller 31 functions as a power supply control device.

When the power supply IC 41 receives a drive instruction signal, it performs the power supply process shown in Figure 4 at predetermined intervals. First, the power supply IC 41 determines whether or not an operating state switching signal has been input, that is, whether or not external charging is in progress (step S101). If this determination result is negative, the power supply IC 41 turns on the first switch SW11 and turns off the second and third switches SW12 and SW13 (step S102). Furthermore, the power supply IC 41 sets the time ratio Ton/Tsw in the control switch circuit 50, where Tsw is the switching period and Ton is the on time (step S103).

Then, with the first switch SW11 still ON, the power supply IC 41 outputs a switching signal to the control switch circuit 50 according to the ratio set in step S103 (step S104). As a result, the switching signal is input to the gate of the control switch 51, and the control switch 51 is turned on and off according to the switching signal. When the control switch 51 is turned on or off, as described above, drive power is supplied to the gate drive circuit DR.

On the other hand, if the result of step S101 is positive, the power supply IC 41 turns off the first switch SW11 and turns on the second and third switches SW12 and SW13 (step S105). The power supply IC 41 also sets the time ratio Ton/Tsw in the control switch circuit 50, where Tsw represents one switching period and Ton represents the on-time (step S106).

Then, with the second and third switches SW12 and SW13 still ON, the power supply IC 41 outputs a switching signal corresponding to the time ratio set in step S106 to the control switch circuit 50 (step S107). As a result, similar to step S104, the control switch 51 is turned on and off, and drive power is supplied to the gate drive circuit DR.

At this time, the second and third switches SW12 and SW13 are turned on, and the power supply IC 41 outputs a switching signal. As a result, the resistor circuit 52 switches to the second resistor R12, which has a higher resistance value than the first resistor R11, making the resistance value of the resistor circuit 52 greater than the normal value (the resistance value of the first resistor R11). Furthermore, in addition to the first snubber circuit 53, the second snubber circuit 54 is also connected to the control switch 51, making the time constant in the snubber circuit 55 greater than the normal value (the time constant of the first snubber circuit 53 alone). Therefore, the switching speed can be slowed down. As a result, the speed at which the control switch 51 switches from on to off or off to on can be slowed down.

Next, the operation and effects of the first embodiment will be described.

Figure 5 shows the noise generated from the switching power supply 40 during its operation. The vertical axis shows the noise magnitude [dBμV], and the horizontal axis shows the noise frequency [MHz]. Figure 5 also illustrates the noise threshold Th defined by regulations for each frequency band. Note that the noise threshold Th is the threshold when the mobile unit is stationary, i.e., during external charging. As shown in Figure 5, the frequency range for which the noise threshold Th is set has defined upper and lower limits. Furthermore, the noise threshold Th differs for each frequency band. For example, the noise threshold Th1 in the low-frequency band is larger than the noise threshold Th2 in the high-frequency band. That is, in the low-frequency band, a larger noise level is acceptable compared to the high-frequency band.

In Figure 5, the noise when the operating state switching signal is not input (i.e., not being externally charged) is shown with a dashed line, and the noise when the operating state switching signal is input (i.e., being externally charged) is shown with a solid line.

As shown in Figure 5, when not being externally charged, i.e., under normal conditions, the noise based on the operation of the switching power supply 40 may exceed the noise threshold Th depending on the frequency band. On the other hand, when being externally charged, the power supply IC 41 slows down the switching speed of the control switch 51 to turn the control switch 51 on and off. As a result, as shown in Figure 5, the magnitude of the noise can be suppressed so as not to exceed the noise threshold Th.
.

Incidentally, even if the switching power supply 40 is operated intermittently, noise in a specific frequency band can be reduced. However, noise in other frequency bands cannot be reduced. In other words, the overall noise level cannot be suppressed, and in some frequency bands, it may exceed the noise threshold Th. On the other hand, in the switching power supply 40 of the first embodiment, the overall noise level is suppressed by slowing down the switching speed. That is, the noise level can be reduced uniformly across all frequency bands, and it is easy to reduce the noise level below the noise threshold Th.

Under normal conditions, when no operating state switching signal is input, the power supply IC 41 switches the resistance value in the resistor circuit 52 to a predetermined normal value and inputs a switching signal to the control switch 51 to control the on/off switching. On the other hand, when an operating state switching signal is input, the power supply IC 41 switches the resistance value in the resistor circuit 52 to a value greater than the normal value and inputs a switching signal to the control switch 51, thereby slowing down the switching speed. More specifically, under normal conditions, the power supply IC 41 turns on the first switch SW11 and inputs a switching signal to the control switch 51 via the first resistor R11. On the other hand, when an operating state switching signal is input, the power supply IC 41 turns on the second switch SW12 and inputs a switching signal via the second resistor R12. This allows for slowing down the switching speed with a simple circuit configuration.

Under normal circumstances, the power supply IC 41 switches the time constant in the snubber circuit 55 to a predetermined normal value and inputs a switching signal to the control switch 51 to control the on/off switching. However, when an operating state switching signal is input, the power supply IC 41 switches the time constant in the snubber circuit 55 to a value greater than the normal value and inputs a switching signal to the control switch 51. That is, under normal circumstances, the power supply IC 41 inputs the switching signal to the control switch 51 with the first snubber circuit 53 connected in parallel to the control switch 51. Then, when an operating state switching signal is input, the power supply IC 41 inputs the switching signal with the first snubber circuit 53 and the second snubber circuit 54 connected in parallel to the control switch 51. This allows for a slower switching speed with a simple circuit configuration.

<Second Embodiment>
Next, a second embodiment will be described in which the configuration of the switching power supply 40 in the first embodiment is changed.

As shown in Figure 6, the switching power supply 140 of the second embodiment differs from the switching power supply 40 of the first embodiment in that it lacks the configuration for slowing down the switching speed, specifically, the second resistor R12 and the second snubber circuit 54. That is, as shown in Figure 6, the power supply IC 41 is connected to the gate of the control switch 51 via the first resistor R11, but it lacks the second resistor R12 and therefore cannot be switched. Furthermore, only the first snubber circuit 53 is connected in parallel to the control switch 51, and there is no configuration to add and connect the second snubber circuit 54 in parallel.

On the other hand, the power supply IC 41 is configured to allow changing the switching frequency. In detail, in the second embodiment, when a drive instruction signal is input, the power supply IC 41 performs the power supply process shown in Figure 7 at predetermined intervals. First, the power supply IC 41 determines whether or not an operating state switching signal has been input (step S201). If this determination is negative, the power supply IC 41 sets the switching frequency (operating frequency) to a predetermined first frequency f1 (step S202). Then, the power supply IC 41 identifies the switching period Tsw1 from the first frequency f1 and sets the time ratio Ton1/Tsw1 (step S203).

Then, the power supply IC 41 outputs a switching signal to the control switch circuit 50 according to the ratio set in step S203 (step S204). At this time, the switching signal is operated at the switching frequency (first frequency f1) set in step S202. As a result, the switching signal is input to the gate of the control switch 51, and the control switch 51 is turned on and off according to the switching signal. When the control switch 51 is turned on or off, drive power is supplied to the gate drive circuit DR, as described above.

On the other hand, if the result of step S201 is positive, the power supply IC 41 sets the switching frequency to a second frequency f2, which is different from the first frequency f1 (step S205). The second frequency f2 is lower than the first frequency f1. Then, the power supply IC 41 identifies the switching period Tsw2 from the second frequency f2 and sets the time ratio Ton2/Tsw2 (step S206). Then, the power supply IC 41 outputs a switching signal corresponding to the time ratio set in step S206 to the control switch circuit 50 (step S207). At this time, the switching signal is operated at the switching frequency (second frequency f2) set in step S205. As a result, the control switch 51 is turned on and off, and drive power is supplied to the gate drive circuit DR.

The operation and effects of the switching power supply 140 of the second embodiment will now be described.

Similar to Figure 5, Figure 8 shows the noise resulting from the operation of the switching power supply 140 of the second embodiment. As shown in Figure 8, the frequency range for which the noise threshold Th is set has defined upper and lower limits. Furthermore, the noise threshold Th differs for each frequency band. For example, the noise threshold Th1 in the low-frequency band is larger than the noise threshold Th2 in the high-frequency band. That is, in the low-frequency band, a larger noise level is acceptable compared to the high-frequency band.

Therefore, in the second embodiment, the power supply IC 41 sets a second frequency f2 as the switching frequency during external charging, which is lower than the normal first frequency f1. That is, during external charging, the power supply IC 41 lowers the switching frequency (operating frequency), shifting the noise frequency overall to the lower frequency side (left side). This moves noise present in the high-frequency band to the low-frequency band, allowing it to fall below the noise threshold Th. Alternatively, it moves the noise to a low-frequency band where the noise threshold Th is not set (a band lower than the lower limit of the threshold Th), thereby satisfying the noise requirement.

Furthermore, in the second embodiment, since the switching speed is not slowed down, heat generation associated with a decrease in switching speed can be suppressed, and power consumption can be reduced.

<Third Embodiment>
Next, a third embodiment will be described in which the configuration of the switching power supply 40 in the first embodiment is changed.

The circuit configuration of the switching power supply 140 in the third embodiment is the same as that of the second embodiment (see Figure 6), so its explanation is omitted. Furthermore, the power supply IC 41 in the third embodiment is configured to allow for changing the switching frequency, similar to the second embodiment.

To explain in detail, in the third embodiment, the power supply IC 41, upon receiving a drive instruction signal, performs the power supply process shown in Figure 9 at predetermined intervals. In the power supply process shown in Figure 9, steps S301 to S304 are the same as steps S201 to S204, and are therefore omitted.

On the other hand, if the result of step S301 is positive, the power supply IC 41 sets the switching frequency to a third frequency f3, which is different from the first frequency f1 (step S305). The third frequency f3 is higher than the first frequency f1. Then, the power supply IC 41 identifies the switching period Tsw3 from the third frequency f3 and sets the time ratio Ton3/Tsw3 (step S306). Then, the power supply IC 41 outputs a switching signal corresponding to the time ratio set in step S306 to the control switch circuit 50 (step S307). At this time, the switching signal is operated at the switching frequency (third frequency f3) set in step S305. As a result, the control switch 51 is turned on and off, and drive power is supplied to the gate drive circuit DR.

The operation and effects of the switching power supply 140 of the third embodiment will now be described.

Similar to Figures 5 and 8, Figure 10 shows the noise resulting from the operation of the switching power supply 40 of the second embodiment. In the third embodiment, the power supply IC 41 sets a third frequency f3 as the switching frequency, which is higher than the normal first frequency f1, during external charging. That is, during external charging, the power supply IC 41 of the third embodiment increases the switching frequency (operating frequency), shifting the noise frequency overall to the higher frequency side (right side). At this time, the noise Ns1, which normally exceeded the noise threshold Th, is shifted so that it falls outside the upper limit of the frequency range where the noise threshold Th is set. This satisfies the noise requirements.

Furthermore, in the third embodiment, since the switching speed is not slowed down, heat generation associated with a decrease in switching speed can be suppressed, and power consumption can be reduced.

(Variant)
A modified example in which some of the configurations of the power supply system of the above embodiment are changed will be described below.

In the above embodiment, the power supply IC 41 may receive the current value from the feedback winding 63 and perform feedback control based on that current value.

• In the above embodiment, the return winding 63 may not be provided.

The first and second embodiments described above may be combined. That is, the power supply IC 41 may turn on the second and third switches SW12 and SW13 to slow down the switching speed and lower the switching frequency (operating frequency).

The first and third embodiments described above may be combined. That is, the power supply IC 41 may turn on the second and third switches SW12 and SW13 to slow down the switching speed and increase the switching frequency.

In the first embodiment described above, either the second resistor R12 or the second snubber circuit 54 may be included. Even including only one of them can slow down the switch switching speed.

In the above embodiment, the switching speed was slowed by switching to the second resistor R12. However, if the resistance value can be changed, the circuit configuration of the resistor circuit 52 may be arbitrarily modified.

In the above embodiment, the switching speed was slowed by connecting the second snubber circuit 54. However, if the configuration allows for changing the time constant, the circuit configuration of the snubber circuit 55 may be arbitrarily changed.

The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor using one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable, non-transitional tangible recording medium.

The following describes the characteristic configurations extracted from each of the embodiments described above.
[Structure 1]
In an isolated power supply device (40) that supplies power to a drive circuit (DR) of a semiconductor device (Sp, Sn),
The primary winding (61) connected to the DC power supply,
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
The switch control unit is an isolated power supply device that, when an operating state switching signal is input, controls the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions.
[Structure 2]
The control switch circuit is,
A control switch (51) connected to the primary winding, which switches between supplying power to and stopping power supply to the primary winding,
The system includes a resistor circuit (52) provided in the electrical path between the gate of the control switch and the switch control unit,
The aforementioned resistor circuit is configured to allow its resistance value to be changed.
The switch control unit,
In normal operation when the aforementioned operating state switching signal is not input, the resistance value in the resistor circuit is switched to a predetermined normal value, and a switching signal for controlling the on/off switching is input to the control switch,
The isolated power supply according to configuration 1, wherein when the operating state switching signal is input, the resistance value in the resistor circuit is switched to a value greater than the normal value, and the switching signal is input to the control switch to slow down the switching speed.
[Structure 3]
The control switch circuit is,
A control switch (51) connected to the primary winding, which switches between supplying power to and stopping power supply to the primary winding,
The system comprises a snubber circuit (55) consisting of a series connection of a capacitor and a resistor, which is connected in parallel to the control switch,
The snubber circuit is configured to allow the time constant to be changed.
The switch control unit,
In normal operation when the aforementioned operating state switching signal is not input, the time constant in the snubber circuit is switched to a predetermined normal value, and a switching signal for controlling the on/off switching is input to the control switch,
The isolated power supply according to configuration 1 or 2, wherein when the operating state switching signal is input, the time constant in the snubber circuit is switched to a value larger than the normal value, and the switching signal is input to the control switch to slow down the switching speed.
[Structure 4]
The isolated power supply unit is mounted on a power supply system (10) capable of external charging, which charges the energy storage device (20) using an external power supply (100).
The semiconductor device is a semiconductor switching element that constitutes an inverter (12) that converts power from the energy storage device and supplies it to the motor.
The drive circuit is a gate drive circuit that inputs an operation signal to the gate of the semiconductor switching element of the inverter.
The isolated power supply device according to any one of configurations 1 to 3, wherein the operating state switching signal is input to the switch control unit during external charging.
[Structure 5]
The inverter is installed in the power supply path between the motor (11) and the energy storage device.
The isolated power supply device according to configuration 4, wherein, during external charging, the semiconductor switching element of the inverter is turned on and off, thereby converting the power of the external power supply by the motor and the inverter and supplying it to the energy storage device.
[Composition 6]
In a power supply system (10) capable of external charging, which charges a power storage device (20) using an external power supply (100), an inverter (12) is provided in the power supply path between the motor (11) and the power storage device,
The drive circuit (DR) for the semiconductor switching elements (Sp, Sn) that constitute the inverter,
An isolated power supply device (40) that supplies power to the aforementioned drive circuit,
The system includes a power control device (31) that controls the isolated power supply device,
The aforementioned isolated power supply device is
The primary winding (61) connected to the DC power supply (21),
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
During external charging, the semiconductor switching element of the inverter is switched on and off, thereby converting the power of the external power supply by the motor and the inverter and supplying it to the energy storage device.
The power control device inputs an operating state switching signal to the switch control unit while external charging is in progress.
The power supply system wherein, when the operating state switching signal is input, the switch control unit controls the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions.
[Structure 7]
In a power control program to be implemented by an isolated power supply unit (40) that supplies power to a drive circuit (DR) of a semiconductor device (Sp, Sn),
The aforementioned isolated power supply device is
The primary winding (61) connected to the DC power supply,
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
A power control program that, when an operating state switching signal is input to the isolated power supply, causes the switch control unit to perform on/off control by changing the switching frequency to one that is different from the normal setting and slowing down the switching speed to one that is slower than the normal setting, or by performing either one of these actions.

10…Power supply system, 11…Motor, 12…Inverter, 20…High-voltage battery, 21…Low-voltage battery, 31…Microcontroller, 40, 140…Switching power supply, 41…Power supply IC, 50…Control switch circuit, 51…Control switch, 61…Input winding, 62…Output winding, 100…External charger, DR…Gate drive circuit.

Claims (5)

In an isolated power supply unit (40, 140) that supplies power to a drive circuit (DR) of a semiconductor device (Sp, Sn),
The primary winding (61) connected to the DC power supply,
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
The isolated power supply unit is mounted on a power supply system (10) capable of external charging, which charges the energy storage device (20) using an external power supply (100).
The semiconductor device is a semiconductor switching element that constitutes an inverter (12) that converts power from the energy storage device and supplies it to the motor.
The drive circuit is a gate drive circuit that inputs an operation signal to the gate of the semiconductor switching element of the inverter.
The inverter is provided in the power supply path between the motor (11) and the energy storage device.
During external charging, the semiconductor switching element of the inverter is switched on and off, thereby converting the power of the external power supply by the motor and the inverter and supplying it to the energy storage device.
The switch control unit is configured to receive an operating state switching signal while external charging is in progress.
The switch control unit is an isolated power supply device that, when an operating state switching signal is input, controls the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions. The control switch circuit is,
A control switch (51) connected to the primary winding, which switches between supplying power to and stopping power supply to the primary winding,
The system includes a resistor circuit (52) provided in the electrical path between the gate of the control switch and the switch control unit,
The aforementioned resistor circuit is configured to allow its resistance value to be changed.
The switch control unit,
In normal operation when the aforementioned operating state switching signal is not input, the resistance value in the resistor circuit is switched to a predetermined normal value, and a switching signal for controlling the on/off switching is input to the control switch,
The isolated power supply device according to claim 1, wherein when the operating state switching signal is input, the resistance value in the resistor circuit is switched to a value greater than the normal value, and the switching signal is input to the control switch to slow down the switching speed. The control switch circuit is,
A control switch (51) connected to the primary winding, which switches between supplying power to and stopping power supply to the primary winding,
The system comprises a snubber circuit (55) consisting of a series connection of a capacitor and a resistor, which is connected in parallel to the control switch,
The snubber circuit is configured to allow the time constant to be changed.
The switch control unit,
In normal operation when the aforementioned operating state switching signal is not input, the time constant in the snubber circuit is switched to a predetermined normal value, and a switching signal for controlling the on/off switching is input to the control switch,
The isolated power supply device according to claim 1, wherein when the operating state switching signal is input, the time constant in the snubber circuit is switched to a value larger than the normal value, and the switching signal is input to the control switch to slow down the switching speed. In a power supply system (10) capable of external charging, which charges a power storage device (20) using an external power supply (100),
An inverter (12) is provided in the power supply path between the motor (11) and the energy storage device,
The drive circuit (DR) for the semiconductor switching elements (Sp, Sn) that constitute the inverter,
An isolated power supply unit (40, 140) that supplies power to the drive circuit,
The system includes a power control device (31) that controls the isolated power supply device,
The aforementioned isolated power supply device is
The primary winding (61) connected to the DC power supply (21),
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
During external charging, the semiconductor switching element of the inverter is switched on and off, thereby converting the power of the external power supply by the motor and the inverter and supplying it to the energy storage device.
The power control device inputs an operating state switching signal to the switch control unit while external charging is in progress.
The power supply system wherein, when the operating state switching signal is input, the switch control unit controls the on/off state by changing the switching frequency to one that is different from the normal state and slowing down the switching speed to one that is slower than the normal state, or by performing either one of these actions. A power supply system (10) capable of performing external charging, which charges a power storage device (20) using an external power supply (100),
An inverter (12) is provided in the power supply path between the motor (11) and the energy storage device,
The drive circuit (DR) for the semiconductor switching elements (Sp, Sn) that constitute the inverter,
An isolated power supply unit (40, 140) that supplies power to the drive circuit,
A power control program to be implemented by the isolated power supply in the power supply system, which includes a power control device (31) that controls the isolated power supply ,
The aforementioned isolated power supply device is
The primary winding (61) connected to the DC power supply,
A secondary winding (62) that can be magnetically coupled to the primary winding via a core,
A control switch circuit (50) that, when turned on, supplies power from the DC power supply to the primary winding, and when turned off, stops the supply of power from the DC power supply to the primary winding,
The system includes a switch control unit (41) that controls the on/off state of the control switch circuit,
During external charging, the semiconductor switching element of the inverter is switched on and off, thereby converting the power of the external power supply by the motor and the inverter and supplying it to the energy storage device.
The power control device is configured to input an operating state switching signal to the isolated power supply device during external charging.
A power control program that, when an operating state switching signal is input to the isolated power supply, causes the switch control unit to perform on/off control by changing the switching frequency to one that is different from the normal setting and slowing down the switching speed to one that is slower than the normal setting, or by performing either one of these actions.