WO-2026094485-A1 - POWER CONVERSION DEVICE AND POWER STORAGE SYSTEM

Abstract

In the present invention, if, after a timer start signal is inputted from a microcontroller 40, a first set time elapses without a clear signal being inputted from the microcontroller 40, then a watchdog timer 50 outputs, to the microcontroller 40, an interrupt signal for starting up an interrupt handler for shutting down DC-DC converters 30a-30d in a normal procedure. If a second set time elapses after a timer start signal is inputted from the interrupt handler of the microcontroller 40, then the watchdog timer 50 outputs a reset signal to the microcontroller 40.

Inventors

• ARATANI Naoki
• TERAI HIROSHI
• HIGA Juan

Assignees

• パナソニックＩＰマネジメント株式会社

Dates

Publication Date

20260507

Application Date

20250926

Priority Date

20241028

Claims (4)

1. A DC/DC converter connected to a battery, A microcontroller that controls the DC/DC converter, The system includes a watchdog timer that monitors whether the microcontroller is operating normally, The aforementioned watchdog timer is If a timer start signal is input from the microcontroller and a first set time has elapsed without a clear signal being input from the microcontroller, an interrupt signal is output to the microcontroller to activate an interrupt handler for terminating the DC/DC converter in the normal procedure. After the timer start signal is input from the interrupt handler of the microcontroller, and a second set time has elapsed, a reset signal is output to the microcontroller. A power conversion device characterized by the following features.
2. The power conversion device according to claim 1, characterized in that the second setting time is set to a shorter time than the first setting time.
3. The DC/DC converter is connected between the battery and the DC bus. The aforementioned DC bus is connected to a load to which backup power should be supplied, and to an AC/DC converter connected to the commercial power grid. The DC/DC converter is A DC/DC converter for charging, Multiple DC/DC converters for discharge connected in parallel, The power conversion device according to claim 1, characterized by including the following:
4. Storage batteries and A power conversion device according to any one of claims 1 to 3, A power storage system characterized by having the following features.

Description

Power conversion devices and energy storage systems This disclosure relates to a power conversion device and energy storage system for charging and discharging batteries. A DC/DC converter is used to charge and discharge batteries. In typical DC/DC converters, feedback control is performed using a microcontroller. The microcontroller calculates the duty cycle of the PWM (Pulse Width Modulation) signal based on the error between the output voltage or output current and the target value, so that the output voltage or output current maintains the target value. If a malfunction occurs in the microcontroller's control, it becomes impossible to properly control the duty cycle of the PWM signal in response to load fluctuations, potentially causing malfunctions such as overcurrent or overvoltage in the DC/DC converter. A watchdog timer is sometimes used as a means of monitoring whether a microcontroller is functioning correctly. A watchdog timer is a timer used to monitor whether there are any abnormalities in the program running on the microcontroller. When the watchdog timer detects that the microcontroller's program has malfunctioned or stopped, it outputs a reset command to the microcontroller, stopping and restarting the program to prevent circuit failure. Patent Document 1 discloses a method for changing the detection time of a watchdog timer in a power tool according to operations such as motor drive and battery charging/discharging, thereby shortening the time from the start of abnormal operation to detection when performing processes with a high risk of failure. It also discloses a method for reducing the risk of circuit failure by equipping the device with two watchdog timers, so that even if one watchdog timer malfunctions, the other watchdog timer can shut down the circuit. Patent Document 2 discloses a method for determining a failure of a current sensing resistor when a reset command for the watchdog timer is input and the current sensing resistor in the power supply circuit is not detecting current. This is a diagram illustrating an example configuration of an energy storage system according to an embodiment.This is a sequence diagram showing an example of fail-safe processing using a watchdog timer, relating to a comparative example.This is a sequence diagram showing an example of fail-safe processing using a watchdog timer according to the embodiment. Figure 1 is a diagram illustrating an example configuration of the energy storage system 1 according to an embodiment. The energy storage system 1 according to this embodiment is used as a power supply system for a data center. Load 3 is a collective term for the numerous servers and storage devices installed in the data center. Load 3 is connected to the DC bus 2. In this embodiment, a 48V DC bus 2 is assumed. The DC bus 2 is connected to an AC/DC converter 5 connected to the commercial power grid 4, an emergency generator 6, and the energy storage system 1. The AC/DC converter 5 converts the AC power supplied from the commercial power grid 4 into DC power while stepping down the voltage, and outputs it to the DC bus 2. For example, it converts the 200-240V AC voltage supplied from the commercial power grid 4 into 48V DC power. The emergency generator 6 is a generator that supplies power to the load 3 in the event of a power outage in the commercial power grid 4. For example, a diesel generator or a gas turbine generator may be used. It takes several tens of seconds to several minutes from the time a power outage in the commercial power grid 4 is detected until the emergency generator 6 starts up. The energy storage system 1 can continue to supply backup power to the load 3 during this time. The energy storage system 1 comprises a battery 10 and a power converter 20. The battery 10 includes multiple (e.g., 9 to 14) cells connected in series. The cells can be lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, etc. Hereinafter, this specification assumes the use of lithium-ion battery cells (nominal voltage: 3.6–3.7V). Note that multiple cells may be connected in parallel in the series stage of each cell to increase capacity. The power conversion device 20 comprises, as its main components, a plurality of parallel-connected (3 in the example shown in Figure 1) discharge DC/DC converters 30a-30c, a charge DC/DC converter 30d, a microcontroller 40, and a watchdog timer 50. Multiple discharge DC/DC converters 30a-30c and a charging DC/DC converter 30d are connected between the battery 10 and the DC bus 2. The number of parallel discharge DC/DC converters 30a-30c is determined according to the power required by the load 3 during a power outage. Alternatively, a single discharge DC/DC converter with high current withstand capability may be used. The charging DC/DC converter 30d does not need high current withstand capability, as it only needs to charge the battery 10 at a low rate from the commercial power grid 4. Switch