Patent Description:
An electric transport refrigeration system including a power generator that is driven by an engine of a vehicle, and a refrigerator that operates with power generated by the power generator is provided. The generated power of the power generator changes with fluctuation of a rotation speed of the engine. Accordingly, there is a need to meet load power of the refrigerator to a condition that the engine rotates at the lowest speed and the generated power of the power generator is the smallest, and power needed for setting a temperature of a cold insulation storage to a desired target temperature may be hardly obtained. In contrast, a transport refrigeration system is known that is mounted with a secondary battery storing generated power in a case where the generated power of a power generator is large and also supplies power from the secondary battery to the refrigerator in a case where the generated power of the power generator is small, thereby coping with the above-described problem.

PTL <NUM> discloses a technique that, in control for driving and stopping a power generator of a so-called microhybrid vehicle having a structure, in which power generated by the power generator with drive of an engine is stored in the secondary battery, extends an interval from the drive to the stop of the power generator in a case where engine efficiency is high, and reduces the interval from the drive to the stop when the engine efficiency becomes low, thereby achieving improvement of fuel efficiency performance of a battery while reducing a load of the engine in a case where the engine efficiency is low.

PTL3 discloses that a refrigerant plant for a vehicle is equipped with a compressor for compressing the refrigerant for freezing, a generator driven by the engine of a vehicle, a battery charged by the generator, a commercial power input part for taking in power from the commercial power source, and a power converter for converting the power inputted from the power source into the power for driving the motor of the compressor and supplying it to the motor of the compressor. The generator, the commercial power input part AC, and the battery are connected in parallel with the power converter.

PTL4 discloses that a refrigeration power system for cooling a storage compartment in a vehicle includes a power source independent of a vehicle battery. The power source provides power to a refrigeration unit that includes a variable speed compressor. The refrigeration power system determines available power and varies the speed of the compressor accordingly to provide a lesser amount of cooling at start-up or when the available power value is less than a required power value. The power system operates the variable speed compressor at the required power value when the available power value is large enough to provide a cooling capacity so that the storage compartment obtains a preselected temperature.

PTL5 discloses that a vehicle refrigeration system is provided for cooling an enclosed space within a trailer. The vehicle refrigeration system includes a compressor unit operatively coupled to a condenser and an evaporator. The compressor unit includes an electric compressor motor coupled to a power controller for coupling motor to either a primary or a secondary source of power, and cycling the compressor motor on and off responsive to a signal from a temperature sensor.

PTL6 discloses a method of operating an internal combustion engine coupled in a hybrid powertrain, the method comprising of extracting waste energy from a component of an electrical power system of the hybrid powertrain, and adjusting intake air temperature during homogeneous charge compression ignition operation of the engine by using said extracted waste energy. PTL <NUM> discloses a battery charge management system of the prior art.

However, in the above-described configuration in which the secondary battery is added as a power supply of the refrigerator, when an operation situation in which the secondary battery is used occurs, the operation is often controlled while lowering the refrigeration ability of the refrigerator, and after all, a sufficient refrigeration ability may not be obtained.

The invention provides a control device, a transport refrigeration system, a control method, capable of solving the above-described problem.

According to the present invention, there is provided a control device as set out in independent claim <NUM>, a transport refrigeration system as set out in independent claim <NUM>, and a control method as set out in independent claim <NUM>. Advantageous developments are defined in the dependent claims.

With the control device, the transport refrigeration system, and the control method described above, in the transport refrigeration system having, as a power supply, the power generator that generates power with the drive of the power source of the moving body, and the secondary battery, it is possible to extend an operation time without lowering a refrigeration ability even in a situation in which the power stored in the secondary battery is used.

Hereinafter, an air conditioner according to an embodiment of the invention will be described referring to <FIG>. <FIG> is a diagram showing an example of a vehicle including a transport refrigeration system according to the embodiment of the invention. A vehicle A is, for example, a truck in which a refrigerator is mounted. As shown in the drawing, the vehicle A includes an engine <NUM> that drives the vehicle A, a cold insulation storage <NUM> that is mounted in a load compartment, a power generator <NUM> for a refrigerator that is driven by the engine <NUM>, a power generator <NUM> for a vehicle that is driven by the engine <NUM>, a battery <NUM> for a refrigerator, a battery <NUM> for a vehicle, and a refrigeration unit <NUM>. The power generator <NUM> for a vehicle and the battery <NUM> for a vehicle are mounted for the purpose of traveling of the vehicle A or supplying power to electric equipment in the vehicle A. The power generator <NUM> for a refrigerator and the battery <NUM> for a refrigerator are mounted for the purpose of supplying power to the refrigeration unit <NUM>. The refrigeration unit <NUM> operates with power (generated power) generated by the power generator <NUM> or the generated power of the power generator <NUM> and power stored in the battery <NUM> as a power supply, and refrigerates a temperature of the inside of the cold insulation storage <NUM> to a temperature desired by a user. Rated voltages of the power generator <NUM> and the battery <NUM> are, for example, <NUM> V or <NUM> V.

<FIG> is a block diagram showing an example of the transport refrigeration system according to the embodiment of the invention. A transport refrigeration system <NUM> includes the power generator <NUM>, the battery <NUM>, and the refrigeration unit <NUM>. The power generator <NUM> is a constant-voltage power generator that generates power with rotation of the engine <NUM>. The power generator <NUM> is connected to the refrigeration unit <NUM>, and the power generated by the power generator <NUM> is supplied to the refrigeration unit <NUM>. The refrigeration unit <NUM> refrigerates the cold insulation storage <NUM> to a desired temperature. The refrigeration unit <NUM> includes a converter <NUM>, an inverter <NUM>, a refrigerator <NUM>, and a controller <NUM>. The converter <NUM> boosts power supplied from the power generator <NUM>. The converter <NUM> outputs the boosted direct-current power to the inverter <NUM>. The inverter <NUM> converts the direct-current power from the converter <NUM> to three-phase alternating-current power having a frequency according to a refrigeration load and supplies the three-phase alternating-current power to an electric compressor <NUM> of the refrigerator <NUM>. The refrigerator <NUM> includes a refrigerant circuit that has a condenser, an evaporator, an expansion valve, and the like (not shown) starting with the electric compressor <NUM>. In a case where the electric compressor <NUM> is driven with power supplied from the inverter <NUM>, a refrigerant is sent out and circulated in the refrigerant circuit by the electric compressor <NUM>. With this, the refrigerator <NUM> refrigerates a space inside the cold insulation storage <NUM> to a temperature set by the user. The controller <NUM> controls the operation of the refrigerator <NUM>. For example, the controller <NUM> controls power supplied to the refrigerator <NUM> through the inverter <NUM>.

Here, an output characteristic of the power generator <NUM> will be described referring to <FIG> is a diagram showing an example of the output characteristic of the power generator according to the embodiment of the invention. In <FIG>, the vertical axis is an output current from the power generator <NUM>, and the horizontal axis is a rotation speed of the power generator <NUM>. In the drawing, reference numeral ID indicates the rotation speed (for example, <NUM> to <NUM> rpm) of the power generator <NUM> while the vehicle A is idling, and the output current in this case is, for example, about <NUM> A. In the drawing, reference numeral MAX indicates the rotation speed (for example, <NUM> to <NUM> rpm) of the power generator <NUM> in a case where a rotation speed of the engine of the vehicle A becomes maximum, and the output current in this case is, for example, about <NUM> A. In this way, the magnitude of the current output from the power generator <NUM> fluctuates two times or more according to a traveling state of the vehicle A. For this reason, there is a possibility that power is short with solely power supplied to the refrigeration unit <NUM> through power generation of the power generator <NUM> depending on a target temperature of the cold insulation storage <NUM> (a load requested by the refrigerator <NUM>) or the traveling state of the vehicle A. In order to supplement the shortage, the transport refrigeration system <NUM> includes the battery <NUM> as an auxiliary power supply.

The battery <NUM> is a secondary battery that stores power generated by the power generator <NUM> and supplies the stored power to the refrigeration unit <NUM>. The battery <NUM> is configured to store surplus power of power (load power) consumed by the refrigeration unit <NUM> out of the direct-current power converted by the converter <NUM> in response to an instruction of the controller <NUM>. In a case where power is short with solely the generated power of the power generator <NUM>, the power stored in the battery <NUM> is configured to be discharged in response to an instruction of the controller <NUM> and be supplied to the inverter <NUM>. The inverter <NUM> converts direct-current power from the battery <NUM> to three-phase alternating-current power having a frequency according to the load power requested by the refrigerator <NUM> and supplies the three-phase alternating-current power to the electric compressor <NUM>.

Here, the relationship between a charging current and an SOC will be described referring to <FIG> is a diagram showing an example of a constant-voltage charging characteristic of the battery according to the embodiment of the invention. In <FIG>, the vertical axis is a value of the charging current, and the horizontal axis is the SOC of the secondary battery. As described above, the output of the power generator <NUM> is a constant voltage (for example, <NUM> V or <NUM> V). Referring to <FIG>, in a case where the SOC of the battery <NUM> is low, a large current flows in the battery <NUM>, and when the SOC becomes high, the current flowing in the battery <NUM> becomes small. For example, while the charging current is about <NUM> A in a case where the SOC is near zero, the charging current decrease to <NUM> to <NUM> A in a case where the SOC exceeds <NUM>%.

A voltage sensor <NUM> and a current sensor <NUM> are provided between the battery <NUM> and the refrigeration unit <NUM>, and a voltage value measured by the voltage sensor <NUM> and a current value measured by the current sensor <NUM> are output to the controller <NUM>. The battery <NUM> is provided with a temperature sensor <NUM>, and a temperature measured by the temperature sensor <NUM> is output to the controller <NUM>. The controller <NUM> calculates the state of charge (SOC: charging rate) of the battery <NUM> using information regarding the voltage value, the current value, and the temperature acquired from the sensors. The controller <NUM> controls charging and discharging of the battery <NUM> according to the SOC of the battery <NUM>, the generated power of the power generator <NUM>, and the load power requested by the refrigeration unit <NUM> while controlling the operation of the refrigerator <NUM>.

The transport refrigeration system <NUM> may further include means for charging the battery <NUM> with power supplied from an external power supply and means for supplying power to the refrigerator. For example, the transport refrigeration system <NUM> further includes a charging device <NUM>, and a charging stand S receives power from an alternating-current power supply V and converts the alternating-current power to direct-current power. Then, in a case where the vehicle A and the charging stand S are connected by a charging cable, the direct-current power is supplied from the charging stand S to the vehicle A side, and the charging device <NUM> charges the battery <NUM>. With such a configuration, even in a state in which the power generator <NUM> is not started, it is possible to perform charging to the battery <NUM> and supply of power to the refrigerator.

Next, the controller <NUM> will be described referring to <FIG> is a functional block diagram showing an example of the controller in the transport refrigeration system according to the embodiment of the invention. The controller <NUM> is, for example, a computer, such as a microcomputer. The controller <NUM> includes a sensor information acquisition unit <NUM>, a charging rate estimation unit <NUM>, a generated power calculation unit <NUM>, a load power information acquisition unit <NUM>, a charging and discharging control unit <NUM>, a target load setting unit <NUM>, an input unit <NUM>, a refrigerator control unit <NUM>, and a storage unit <NUM>.

The sensor information acquisition unit <NUM> acquires the voltage value measured by the voltage sensor <NUM>, the current value measured by the current sensor <NUM>, and the temperature measured by the temperature sensor <NUM>. The sensor information acquisition unit <NUM> acquires a rotation speed from a rotation sensor (not shown) that measures the rotation speed of the power generator <NUM> (or a rotation sensor that measures the rotation speed of the engine <NUM>).

The charging rate estimation unit <NUM> calculates the SOC of the battery <NUM> based on the voltage value and the current value acquired by the sensor information acquisition unit <NUM>. For example, the charging rate estimation unit <NUM> calculates the SOC (referred to as an initial SOC) of the battery <NUM> based on an open circuit voltage (OCV) measured by the voltage sensor <NUM> in a case where a predetermined time has elapsed after the operation of the refrigerator <NUM> is stopped, and the battery <NUM> is in a balanced state, a function indicating the relationship between the open circuit voltage and the SOC of the battery <NUM>, and the like. In a case where the refrigerator <NUM> starts the operation, the charging rate estimation unit <NUM> integrates the current value (charging current or discharging current) measured by the current sensor <NUM> to the initial SOC to calculate a current SOC of the battery <NUM> (current integration method). Since the battery <NUM> changes in resistance value according to the temperature, temperature correction may be performed on the calculated SOC. For example, the charging rate estimation unit <NUM> calculates a correction amount according to the temperature measured by the temperature sensor <NUM> using a predetermined SOC correction value calculation model for defining a correction amount of the SOC according to the temperature of the battery <NUM> and adds the correction amount to the SOC calculated by the current integration method to calculate the SOC.

The generated power calculation unit <NUM> calculates the generated power of the power generator <NUM>. For example, the generated power calculation unit <NUM> calculates the generated power (W) by obtaining an output current from the rotation speed of the power generator <NUM> acquired by the sensor information acquisition unit <NUM> based on a graph illustrated in <FIG> and multiplying an output voltage (for example, <NUM> V) by the output current.

The load power information acquisition unit <NUM> acquires information regarding power needed for the operation of the refrigerator <NUM>. For example, the load power information acquisition unit <NUM> acquires information regarding power consumption from the inverter <NUM>. For example, the load power information acquisition unit <NUM> acquires a detection value of power consumption of the refrigerator <NUM>.

In a case where the generated power of the power generator <NUM> is smaller than the load power of the refrigerator <NUM>, the charging and discharging control unit <NUM> supplies the power stored in the battery <NUM> to the inverter <NUM> when the SOC of the battery <NUM> is equal to a predetermined threshold value (first threshold value) or more. In this case, the charging and discharging control unit <NUM> permits the load power at which the SOC of the battery <NUM> decreases, and supplies power matching a shortage obtained by subtracting the generated power from the load power from the battery <NUM> to the inverter <NUM>. In a case where the power stored in the battery <NUM> is supplied to the inverter <NUM>, the charging and discharging control unit <NUM> stops the supply of the power from the battery <NUM> to the inverter <NUM> when the SOC of the battery <NUM> becomes smaller than a predetermined threshold value (second threshold value). In a situation in which the power stored in the battery <NUM> is not supplied to the inverter <NUM>, the charging and discharging control unit <NUM> supplies a surplus of the power generated by the power generator <NUM> to the battery <NUM> to charge the battery <NUM>.

In a case where the supply of the power from the battery <NUM> to the inverter <NUM> is performed, the target load setting unit <NUM> reduces the load such that the amount of power consumed by the load becomes smaller than the amount of power generated by the power generator <NUM> when the SOC of the battery <NUM> becomes smaller than the second threshold value. For example, in a case where the generated power of the power generator <NUM> is smaller than the load power of the refrigerator <NUM>, the target load setting unit <NUM> reduces the load power such that the load power of the refrigerator <NUM> becomes smaller than the generated power of the power generator <NUM> when the SOC of the battery <NUM> becomes smaller than the second threshold value. Alternatively, the target load setting unit <NUM> may reduce the load power, for example, such that a predetermined charging current (for example, a charging current according to the SOC based on a charging and discharging current illustrated in <FIG>) flows into the battery <NUM>. Otherwise, for example, the load so far may be maintained for a time as long as possible, and then, the load is decreased sharply, whereby control may be performed such that the amount of power consumption of the load until a predetermined time elapses after the SOC falls below the second threshold value becomes smaller than the amount of power generated by the power generator <NUM>. On the other hand, in a case where the SOC of the battery <NUM> is equal to the second threshold value or more, and the total of the amount of power generated by the power generator <NUM> and the amount of power supplied from the battery <NUM> can meet the amount of power consumed by the load, the target load setting unit <NUM> maintains the load as it is.

The input unit <NUM> receives an input of information regarding the target temperature of the cold insulation storage <NUM> or information for instructing the start and stop of the refrigerator <NUM> from the user. The refrigerator control unit <NUM> controls the operation of the refrigerator <NUM>. For example, in a case where the user performs an operation to start the operation of the refrigerator <NUM>, the refrigerator control unit <NUM> outputs a control signal for instructing the start to the refrigerator <NUM> side through the inverter <NUM>. In the refrigerator <NUM>, the electric compressor <NUM> is started based on the control signal, and the refrigerator <NUM> starts the operation. In a case where the user sets the target temperature of the cold insulation storage <NUM>, the refrigerator control unit <NUM> generates a control signal according to the target temperature based on a temperature of the inside of the cold insulation storage <NUM>, an ambient temperature, or the like and performs frequency adjustment or the like of the inverter <NUM> to control an operation state of the refrigerator <NUM>. For example, in a case where the user performs an operation to stop the operation of the refrigerator <NUM>, the refrigerator control unit <NUM> outputs a control signal for stopping the operation of the refrigerator <NUM>, the refrigerator <NUM> stops the operation in response to the control signal. The storage unit <NUM> stores various kinds of information, such as the first threshold value and the second threshold value.

Next, charging and discharging control of the embodiment will be described referring to <FIG> is a diagram illustrating the charging and discharging control of the transport refrigeration system according to the embodiment of the invention. <FIG> shows the relationship of a graph ((a) of <FIG>) of a frequency of the power generator <NUM> in a time series, a graph ((b) of <FIG>) of the load power of the refrigerator <NUM> in a time series, a graph ((c) of <FIG>) of the charging and discharging current of the battery <NUM> in a time series, and a graph ((d) of <FIG>) of the SOC of the battery <NUM> in a time series. The horizontal axis of each graph indicates the lapse of time, and the same position on the horizontal axis of each graph indicates the same time.

First, at time <NUM>, the engine <NUM> of the vehicle A is started. In a case where the engine <NUM> is started, the rotation speed of the power generator <NUM> increases according to the rotation speed of the engine <NUM> and is maintained at a constant rotation speed in an idling state ((a) of <FIG>). In this case, the refrigerator <NUM> is not operated, and accordingly, the load power is zero ((b) of <FIG>). Since the load power is zero, the entire generated power of the power generator <NUM> for a refrigerator becomes a surplus. The charging and discharging control unit <NUM> assigns the entire generated power of the power generator <NUM> to the charging of the battery <NUM> ((c) of <FIG>). In the meantime, the SOC of the battery <NUM> increases ((d) of <FIG>).

In a case where the vehicle A starts traveling at time T0, the rotation speed of the power generator <NUM> increases and fluctuates for a while ((a) of <FIG>). Next, the refrigerator <NUM> is stopped, and the load power is zero ((b) of <FIG>). The charging and discharging control unit <NUM> assigns the entire generated power of the power generator <NUM> to the charging of the battery <NUM> ((c) of <FIG>). The SOC of the battery <NUM> continues to increase ((d) of <FIG>).

Thereafter, the vehicle A travels at a constant speed. The rotation speed of the power generator <NUM> becomes constant ((a) of <FIG>). On the other hand, the refrigerator <NUM> starts the operation at time T1, and performs the operation with constant load power w1 with respect to the target temperature set by the user ((b) of <FIG>). In the example, it is assumed that the generated power of the power generator <NUM> is greater than the load power w1 according to the operation of the refrigerator <NUM>. In this case, the charging and discharging control unit <NUM> assigns the surplus (the generated power - the load power w1) of the generated power of the power generator <NUM> to the charging of the battery <NUM> ((c) of <FIG>). In the example, it is possible to charge the same power even after time T1. Next, the SOC of the battery <NUM> continues to increase ((d) of <FIG>). The SOC of the battery <NUM> becomes the first threshold value at time T1'. The first threshold value is a threshold value of the SOC at which the start of discharging of the battery <NUM> is permitted in the charging and discharging control of the embodiment.

In a case where the SOC of the battery <NUM> becomes equal to the first threshold value or more, and the load power w1 exceeds the generated power, the charging and discharging control unit <NUM> starts the supply of the power from the battery <NUM> to the refrigeration unit <NUM>. As described below, the charging and discharging control unit <NUM> performs control of charging and discharging and control of the load power such that the SOC of the battery <NUM> does not fall below the second threshold value (for example, the SOC in a case where the refrigerator <NUM> starts the operation). It is assumed that the SOC (the SOC at time T1) in a case where the refrigerator <NUM> starts the operation is the second threshold value. The second threshold value is a lowest value of the SOC that the battery <NUM> can take in the charging and discharging control of the embodiment. That is, even though the battery <NUM> is being discharged, the SOC of the battery <NUM> is controlled to be maintained to be the second threshold value or more by the charging and discharging control unit <NUM>. A condition may be made that the SOC of the battery <NUM> becomes equal to the second threshold value or more at the time at which the refrigerator <NUM> starts the operation.

Thereafter, the vehicle A reduces the speed, and accordingly, the rotation speed of the power generator <NUM> also decreases ((a) of <FIG>). The refrigerator <NUM> continues the operation with the same load power w1 ((b) of <FIG>). With a decrease in the power generated by the power generator <NUM>, at time T3, a charging current value flowing in the battery <NUM> by the charging and discharging control unit <NUM> starts to decrease ((c) of <FIG>). At time T4, the magnitude of the power generated by the power generator <NUM> becomes equal to the magnitude of the load power w1 of the refrigerator <NUM>. After time T4, the power generated by the power generator <NUM> becomes smaller than the load power w1 of the refrigerator <NUM>. Then, when time T5 is reached, traveling of the vehicle A is brought into the idling state. Accordingly, the charging and discharging control unit <NUM> stops the charging of the battery <NUM> at time T4. After time T4, since the generated power of the power generator <NUM> becomes short with respect to the load power w1 requested by the refrigerator <NUM>, the charging and discharging control unit <NUM> covers the shortage (the load power w1 - the generated power) with discharging from the battery <NUM>. In this case, a condition is made that the SOC of the battery <NUM> becomes equal to the first threshold value or more. In the example, at time T4, since the SOC of the battery <NUM> becomes equal to the first threshold value or more ((d) of <FIG>), the condition is satisfied. The charging and discharging control unit <NUM> discharges the battery <NUM> ((c) of <FIG>), and supplies the power stored in the battery <NUM> to the refrigerator <NUM> through the inverter <NUM>. With this, after time T4, the SOC of the battery <NUM> starts to decrease ((d) of <FIG>). Even though the supply of the power from the battery <NUM> is started, in a case where the SOC is equal to the second threshold value or more, the load power is maintained at w1 by the target load setting unit <NUM>, and thus, the operation of the refrigerator <NUM> is not limited. Accordingly, even after time T4, the temperature of the cold insulation storage <NUM> is controlled to a desired target temperature.

For a while from time T5, the vehicle A is stopped in the idling state. In the interim, the rotation speed of the power generator <NUM> is constant ((a) of <FIG>). In the meantime, since the generated power of the power generator <NUM> falls below the load power w1, and the SOC of the battery <NUM> is equal to the second threshold value or more, the charging and discharging control unit <NUM> continues the discharging of the battery <NUM> ((c) of <FIG>). Accordingly, the SOC of the battery <NUM> continues to decrease ((d) of <FIG>). The load power is maintained at w1 by the target load setting unit <NUM> ((b) of <FIG>). In the meantime, the temperature of the cold insulation storage <NUM> is controlled to the target temperature desired by the user.

When time T6 is reached, the vehicle A starts traveling, and the rotation speed and the generated power of the power generator <NUM> are increasing. With the increase in generated power of the power generator <NUM>, the charging and discharging control unit <NUM> decreases discharge power of the battery <NUM> ((c) of <FIG>), and performs control such that the total of the generated power of the power generator <NUM> and the discharge power of the battery <NUM> becomes equal to the load power w1. Thereafter, at time T7, when the generated power of the power generator <NUM> becomes equal to the load power w1 of the refrigerator <NUM> ((a) of <FIG>), the charging and discharging control unit <NUM> stops the discharging of the battery <NUM> at time T7 ((c) of <FIG>). Thereafter, the rotation speed of the power generator <NUM> continues to increase, and the generated power also increases and exceeds the load power w1. Accordingly, after time T7, the charging and discharging control unit <NUM> supplies the surplus of the generated power of the power generator <NUM> to the battery <NUM> to charge the battery <NUM> ((c) of <FIG>). With this, the SOC of the battery <NUM> increases.

At time T8, the vehicle A further reduces the speed and is brought into the idling state. The rotation speed and the generated power of the power generator <NUM> decrease ((a) of <FIG>). Then, when the generated power of the power generator <NUM> becomes equal to the load power w1 or less, the charging and discharging control unit <NUM> discharges the battery <NUM> based on a state in which the SOC of the battery <NUM> is equal to the first threshold value or more and supplements the shortage of the generated power with respect to the load power ((c) of <FIG>). With this, the SOC of the battery <NUM> decreases ((d) of <FIG>). In the meantime, the operation of the refrigerator <NUM> is not limited based on a state in which the SOC of the battery <NUM> is equal to the second threshold value or more, and the temperature of the cold insulation storage <NUM> is controlled to the target temperature desired by the user.

When time T9 is reached, the SOC of the battery <NUM> reaches the second threshold value. When this happens, the charging and discharging control unit <NUM> stops the discharging of the battery <NUM> at time T9 ((c) of <FIG>). Since the vehicle A continues to be in the idling state even after time T9, the generated power of the power generator <NUM> still falls below the load power w1. Since the discharging of the battery <NUM> is stopped based on a state in which the SOC decreases and reaches the second threshold value, it is not possible to maintain the load power w1 as it is. Accordingly, the target load setting unit <NUM> reduces the load such that the amount of power consumed by the load becomes equal to the amount of power generated by the power generator <NUM> or less. For example, the target load setting unit <NUM> reduces the load power from w1 to w2 ((b) of <FIG>). For example, the load power w2 is set to a value smaller than the generated power of the power generator <NUM> in a case where the vehicle A is brought into the idling state by the target load setting unit <NUM>. The load power is reduced to w2, whereby surplus power remains even though the generated power of the power generator <NUM> is supplied to the refrigerator <NUM>. The charging and discharging control unit <NUM> supplies the surplus power to the battery <NUM> to charge the battery <NUM>. With this, the SOC of the battery <NUM> increases, and then, is recovered to the first threshold value or more. In a case where the SOC of the battery <NUM> is recovered to the first threshold value or more, the charging and discharging control unit <NUM> enables the discharging of the battery <NUM>. In a case where the SOC of the battery <NUM> is recovered to the first threshold value or more, the target load setting unit <NUM> may return the load power from w2 to w1 as an original value. For example, in a case where the temperature of the cold insulation storage <NUM> is sufficiently refrigerated, or the like, control may be performed such that the load power w2 is significantly reduced (for example, w2 = <NUM> may be temporarily set), a charging current as large as possible (for example, a maximum charging current according to the SOC based on the graph illustrated in <FIG>) flows in the battery <NUM> to rapidly recover the SOC of the battery <NUM>, and the original target temperature is returned in a time as short as possible. There is a possibility that the load power decreases to w2 to cause degradation of a refrigeration ability, and the temperature of the cold insulation storage <NUM> increases; however, the charging and discharging control of the embodiment is performed, whereby it is possible to extend the operation time of the refrigerator <NUM> while maintaining the load power w1 according to the target temperature desired by the user.

In the related art, in a situation in which the refrigerator is operated with power from the battery, control is often performed such that the refrigeration ability of the refrigerator <NUM> is saved (the target temperature increases) in order to restrain battery exhaustion. In such control, in a case where the time for which the generated power is short is continued long, and in the meantime, the refrigeration ability of the refrigerator <NUM> is saved. With this, there is a high possibility that the temperature of the cold insulation storage <NUM> increases. In contrast, with the charging and discharging control of the embodiment, even in an operation state in which the battery <NUM> is used, it is possible to extend the time for which the refrigeration ability of the refrigerator <NUM> is utilized to the maximum without saving the refrigeration ability of the refrigerator <NUM> according to the SOC of the battery <NUM>. With this, it is possible to reduce a risk that an inside temperature of the cold insulation storage <NUM> is deviated from the target temperature desired by the user.

Next, a flow of processing of the charging and discharging control of the embodiment in a state in which the engine <NUM> is being driven will be described. <FIG> is a flowchart showing an example of the charging and discharging control of the transport refrigeration system according to the embodiment of the invention. First, the sensor information acquisition unit <NUM> acquires the open circuit voltage of the battery <NUM> measured by the voltage sensor <NUM> in a state regarded as a no-load state in which the refrigerator <NUM> is not started. Next, the charging rate estimation unit <NUM> calculates the initial SOC of the battery <NUM> based on the acquired voltage (Step S11). The charging rate estimation unit <NUM> records the value of the calculated initial SOC in the storage unit <NUM>. Next, the refrigerator <NUM> starts the operation (Step S12). In a case where the refrigerator <NUM> starts the operation, the refrigerator control unit <NUM> drives the electric compressor <NUM> through the inverter <NUM>. The refrigerator control unit <NUM> controls the frequency of the inverter <NUM> to operate the refrigerator <NUM> such that the inside temperature of the cold insulation storage <NUM> becomes the target temperature set by the user through the input unit <NUM> according to various operation conditions, such as the inside temperature of the cold insulation storage <NUM> and an outside temperature.

The generated power calculation unit <NUM> calculates the generated power by obtaining the output current from the rotation speed of the power generator <NUM> acquired by the sensor information acquisition unit <NUM>, for example, based on the graph of <FIG> and multiplying the output current by the voltage (Step S13). The generated power calculation unit <NUM> outputs the value of the calculated generated power to the charging and discharging control unit <NUM>. The load power information acquisition unit <NUM> acquires the value of the load power from the inverter <NUM> (Step S14). The load power information acquisition unit <NUM> outputs the acquired value of the load power to the charging and discharging control unit <NUM>. The charging and discharging control unit <NUM> compares the generated power with the load power (Step S15). In a case where the generated power is equal to the load power or more (Step S15; Yes), the charging and discharging control unit <NUM> supplies the surplus of the generated power obtained by subtracting the load power from the generated power to the battery <NUM> to charge the battery <NUM> (Step S16). The sensor information acquisition unit <NUM> acquires the value of the charging current flowing in the battery <NUM> measured by the current sensor <NUM>. The charging rate estimation unit <NUM> integrates the current value measured by the current sensor <NUM> and adds the integrated value to the initial SOC to calculate the SOC of the battery <NUM> during charging (Step S17). In this case, the charging rate estimation unit <NUM> may correct the SOC based on the internal temperature of the battery <NUM> measured by the temperature sensor <NUM>. The charging rate estimation unit <NUM> records the value of the calculated SOC in the storage unit <NUM>.

In a case where the generated power is smaller than the load power (Step S15; No), the charging and discharging control unit <NUM> determines whether or not the SOC of the battery <NUM> is equal to the first threshold value or the more (Step S18). In a case where the SOC of the battery <NUM> is equal to the first threshold value or more (Step S18; Yes), the charging and discharging control unit <NUM> discharges the battery <NUM> and supplies the shortage of the power obtained by subtracting the generated power from the load power from the battery <NUM> to the inverter <NUM> (Step S19). The sensor information acquisition unit <NUM> acquires the value of the discharging current flowing from the battery <NUM> measured by the current sensor <NUM>. The charging rate estimation unit <NUM> integrates the current value measured by the current sensor <NUM> and calculates the SOC of the battery <NUM> during discharging (Step S20). As in Step S17, the charging rate estimation unit <NUM> may correct the SOC according to the temperature.

In a case where the SOC of the battery <NUM> is less than the first threshold value (Step S18; No), subsequently, the charging and discharging control unit <NUM> determines whether or not the SOC of the battery <NUM> is equal to the second threshold value or more (Step S21). In a case where the SOC of the battery <NUM> is equal to the second threshold value or more (Step S21; Yes), the processing after Step S15 is repeated. In a case where the SOC of the battery <NUM> is less than the second threshold value (Step S21; No), the charging and discharging control unit <NUM> stops the discharging of the battery <NUM> (Step S22). Since the load of the refrigerator <NUM> cannot be supplemented with solely the generated power of the power generator <NUM>, the target load setting unit <NUM> reduces the load such that the amount of power consumed by the load becomes smaller than the amount of power generated by the power generator <NUM> (Step S23). For example, the target load setting unit <NUM> sets a target value of the load power so as to be equal to the generated power of the power generator <NUM> or less regardless of the traveling state of the vehicle A and outputs the newly set target value of the load power to the refrigerator control unit <NUM>. Alternatively, for example, a reference value of the charging current to the battery <NUM> may be provided based on the graph of <FIG>, and the load power may be set such that the value of the charging current measured by the current sensor <NUM> becomes equal to the reference value or more. The refrigerator control unit <NUM> decreases the frequency of the inverter <NUM> according to the load power set by the target load setting unit <NUM>. With this, it is possible to decrease the load power according to the operation of the refrigerator <NUM>.

Next, the refrigerator control unit <NUM> determines whether or not to stop the operation of the refrigerator <NUM> (Step S24). For example, in a case where the user inputs an operation to stop the operation of the refrigerator <NUM> through the input unit <NUM>, the refrigerator control unit <NUM> determines to stop the operation of the refrigerator <NUM>. In a case where the operation of the refrigerator <NUM> is stopped (Step S24; Yes), the flowchart ends.

In a case where the operation of the refrigerator <NUM> is continued (Step S24; No), the processing from Step S13 is repeated. For example, in a case where the load is reduced in the processing of Step S23, the load decreases to cause a decrease in rotation speed of the electric compressor <NUM>, and the refrigeration ability for the cold insulation storage <NUM> decreases; however, in the determination of Step S15, the generated power becomes equal to the load power or more, and the charging and discharging control unit <NUM> charges the battery <NUM>. With this, the SOC of the battery <NUM> is gradually recovered, and then, when the SOC of the battery <NUM> becomes equal to the first threshold value or more, the battery <NUM> is brought into a state capable of being discharged again.

According to the embodiment, since the excess or shortage of the generated power of the power generator <NUM> with respect to the load power can be supplemented by the battery <NUM>, for example, it is possible to perform a stable operation of the refrigerator <NUM> even in a case where fluctuation in generated power of the power generator <NUM> is large due to sharp change in traveling state of the vehicle A (start or stop, change in traveling speed, or the like). For example, it is possible to exhibit the same refrigeration ability as during traveling even though the vehicle A is stopped in the idling state. In particular, in a state in which the SOC of the battery <NUM> is high, it is possible to supply the load power that exceeds the generated power of the power generator <NUM>, and to provide a large refrigeration ability. When the SOC of the battery <NUM> is equal to the second threshold value or more, until the SOC finally decrease to the second threshold value or less, and the discharging of the battery <NUM> is stopped, it is possible to continuously supply the load power equal to the generated power of the power generator <NUM> or more. Accordingly, compared to the control in the related art that the refrigeration ability is saved in a case where the discharging of the battery is performed, it is possible to exhibit the refrigeration ability for a long time, and thus, it becomes easy to control the inside temperature of the cold insulation storage <NUM> to a desired temperature.

In a situation in which the generated power exceeds the load power, the battery <NUM> is charged with the surplus power and the SOC of the battery <NUM> is maintained high, whereby it is easy to maintain a state in which power can be supplied from the battery <NUM>, and it is possible to implement a more stable operation. In a scene where the discharging of the battery <NUM> becomes large, it is possible to maintain the SOC to be equal to the second threshold value or more, and thus, it is possible to restrain early deterioration (sulfation) of the battery <NUM> due to excessive discharging. Furthermore, it is possible to indirectly ascertain the excess or shortage of the generated power with respect to the load power with the charging and discharging current value to the battery <NUM>.

In performing the above-described control, although the charging and discharging is controlled based on the SOC of the battery <NUM> or the load requested by the refrigerator <NUM> is reduced, to this end, there is a need to accurately detect the SOC of the battery <NUM>. With the charging rate estimation unit <NUM> of the embodiment, it is possible to calculate the SOC of the battery <NUM> in real time based on the charging and discharging current from the battery <NUM>.

The constituent elements in the above-described embodiment can be appropriately replaced with the known constituent elements without departing from the spirit and scope of the invention. The technical scope of the invention is not limited to the above-described embodiment, and various alterations may be made without departing from the spirit and scope of the invention. For example, the transport refrigeration system <NUM> can be applied to an aircraft or a ship, as well as a vehicle. The controller <NUM> is an example of a control device. The vehicle A is an example of a moving body. The engine <NUM> is an example of a power source of the moving body. As another example of the power source of the moving body, for example, a motor is exemplified.

Claim 1:
A control device for a refrigerator (<NUM>) having, as a power supply, a power generator (<NUM>, <NUM>) that is driven by an engine or a motor which is a power source of a moving body, and a battery (<NUM>, <NUM>) that stores power generated by the power generator (<NUM>, <NUM>),
wherein, in a case where the power generated by the power generator (<NUM>, <NUM>) is smaller than a load requested by the refrigerator (<NUM>), supply of the power stored in the battery (<NUM>, <NUM>) to the refrigerator (<NUM>) is started in a case where a state of charge (SOC) of the battery (<NUM>, <NUM>) is equal to a predetermined first threshold value or more, and the supply of the power from the battery (<NUM>, <NUM>) for covering shortage of the power generated by the power generator (<NUM>, <NUM>) with respect to the load is permitted until the SOC reaches a predetermined second threshold value,
wherein, in a case where the supply of the power from the battery (<NUM>, <NUM>) to the refrigerator (<NUM>) is performed, the load requested by the refrigerator (<NUM>) is reduced when the state of charge (SOC) of the battery (<NUM>, <NUM>) becomes smaller than a predetermined second threshold value, and
wherein, in a case of reducing the load, the load is reduced such that an amount of power consumed by the load becomes smaller than an amount of power generated by the power generator (<NUM>, <NUM>), and a surplus of the power generated by the power generator (<NUM>, <NUM>) is supplied to charge the battery (<NUM>, <NUM>) until the state of charge (SOC) of the battery (<NUM>, <NUM>) recovers to the first threshold, then the load requested by the refrigerator (<NUM>) is returned to an original value before reduction when the SOC recovers to the first threshold.